Interesting article. After reading it once and scanning it a couple of times for its main arguments, I have some thoughts. The first is a very nonspecific quantum mechanics one that's not of much interest, the second is the evolutionary argument.

The evolutionary argument itself

The evolutionary argument is interestingly not by itself an argument against metaphysical realism. Its conclusion is that our perceptions of the external world are unreliable. This is not the claim that all empirical features of the world are misleading, since the evolutionary consideration in question is that perception does not track truth but is radically biased towards features that are fitness non-neutral. This doesn't imply that every individual perception is a misrepresentation, since any number could be veridical by accident or possibly even veridical because undistorted by the fitness bias. What it does seem to imply is that we can't tell which perceptions are true based on perception alone. (For example, we can't tell whether a visual perception is true by checking with the other senses, since they could all be distorted too.)

First question

Does the evolutionary argument then entail idealism or external-world skepticism? Only if the unreliability of our perceptions of the nature of the external world entails, respectively, the falsity or the untrustworthiness of our experience (perceptual or otherwise) of the existence of the external world.

Second question

Does it entail that, whether or not we can know the external world exists, we can't know (or have justified belief about) what it's like? Only if it's true that (1) the perceptual distortion by the fitness bias implies that the veridicality of no perception is determinable by perception alone, and (2) there is no (wholly or partly) non-perceptual way of determining either the veridicality of our perceptions or the nature of the external world. (If there were extra-sensory ways of knowing what the physical world was like, the unreliability of sense experience wouldn't be troubling.)

Getting from skepticism about the nature of the external world to idealism

The article doesn't go far enough down this road to argue for either (1) or (2), but both are at least plausible. So far Hoffman has then got us to skepticism about the nature of the external world. From here it takes some arguments to the effect that (3) this skepticism about the nature of the external world implies skepticism about its very existence, and (4) skepticism about the existence of the external world implies idealism. The article actually does some work towards (3) in that it anticipates an objection to it, possibly undermining its main opposition.

The objection is that the non-existence of the external world would seem to imply the non-existence of the evolutionary conditions that supposedly led to the fitness bias in our perception, since these are environmental conditions in the physical world. So regardless of whether we can know or justifiably believe anything about the way the world is, we have to believe it exists if we're pushing the evolutionary argument. Hoffman undercuts this worry by saying the role we think the world plays, other observers can play. The evolutionary conditions that caused my perception and its biases lie in other consciousnesses' experiences, in a "conscious circuit" or "network". This simultaneously gives Hoffman a parsimony argument for (4).

Can Hoffman avoid skepticism about the "circuit"?

Interestingly though, it seems that since Hoffman preserves the evolutionary conditions that give rise to our perceptual-representational distortions, he also preserve the distortions. What are our perceptual representations of? Hoffman doesn't go in for solipsism but keeps separate individual consciousnesses which influence each other. So there is in Hoffman's ontology a sort of world that is external to any individual mind, namely W: the set of all conscious experiences of all minds, minus that one. The question is, when Hoffman endorses the fitness bias argument, does he commit himself to skepticism about the nature (or possibly existence) of any "external" world -- observer-independent or not?

Arguments that he can't

So is there a world for my perceptual representations to be unreliable to under Hoffman's intersubjective idealism? And do evolutionary conditions make them actually unreliable? Hoffman says I must take my perceptions seriously because they (or whatever they're of) can negatively impact my consciousness. Under realism, according to Hoffman, the sorts of realities our perceptions are unreliable to include the sorts of realities that impact our consciousness (distorting them towards increased salience), since they include the fitness non-neutral ones. Examples are snakes and trains. They also include realities that don't (distorting them towards decreased salience), presumably including the experiences conscious creatures are undergoing in distant parts of the circuit. It's not clear why our perceptions should not also be unreliable to these realities under intersubjective idealism.

In addition, the sorts of things capable of killing me and ending my consciousness must presumably be the sorts of things capable of existing beyond the end of my consciousness. The only other place for them to exist is W. So mustn't some of my perceptual representations be, indirectly, of things external to my consciousness, just as they would be under realism? And mustn't the evolutionary argument make these unreliable under intersubjective idealism as well? In other words, is there anything about Hoffman's evolutionary argument that restricts its scope to indirect perceptions of observer-independent worlds?

Final thoughts

According to this line of thinking, then, Hoffman's idealism implies skepticism about the nature of the (purely conscious circuit) world external to the individual mind. From there the previous arguments I canvassed pick up and carry us to skepticism about the very existence of that world, and from there to solipsism. So it turns out my arguments take a familiar route in critiques of idealism. Probably they could be met by a less superficial presentation of Hoffman's views.

TL;DR

Nah.