[I started this conversation saying I wouldn't engage you, but I've (obviously) reversed my position. I think the thread is deleted, so it may just be us two in here].

As for Making Assumptions About You:

The question is not whether I'm making assumptions. The question is whether my assumptions are reasonable. There are certain groups on Reddit which promote ideas I don't agree with. I have engaged members of those groups on those ideas. There are nuances (no group is a monolith), but the overall body of philosophy is unhelpful and toxic.

So, when I see that you're an active poster in not just one but several of those groups, that gives me a reasonable basis to conclude you subscribe to those toxic ideas. I did subsequently dig deeper specifically because I wanted to be sure to give you a fair shake. I haven't specifically seen you say anything that shocks my conscience, though your membership in those groups is at still least concerning.

On Engaging You On Ideas

One of the myths of the marketplace of ideas is that it somehow implies that people must have the same conversations over and over for it to be a "marketplace." But this isn't true. There are all sorts of ways that the market applies force. One is social and intellectual shunning.

Let's take a more extreme example just to illustrate. Let's say you were an avid poster to /r/coontown. I'm not saying you are, and i'm not trying to be incendiary. It's just an example that I hope we can agree on. The marketplace of ideas wouldn't require that I argue with you about it at that point. It's a completely acceptable use of the market for me to simply shun you to devalue those bad ideas.

I recognize that there is a tension between shunning and open debate. It's a blurry line. In this case, there has been some well-documented tension between the forums you are involved in and this one, including some extremely detestable and unprovoked personal attacks on friends of mine here.
That leads me to think that reasonable discussion can't happen.