You’ve missed the whole point of that poster’s well-thought-out analogy, and your “logic” leaves much to be desired.

I think you didn't understand my logic if you think that I missed the logic of the person I answered.

But we can certainly have opinions about whether or not they are “true” feminists

Yes you certainly can, but "babylock" is of the opinion that a trans-exclusionary cis rights activist who argues against the validity of trans women is a feminist. I disagree. Since they wrote a top comment it must mean that believing transphobic people can be feminist is a "feminist perspective".

There’s a firm, clearly defined center to the movement.

I honestly don't think so. If this was true then you would have no problem to tell me what disqualifies someone from being a feminist.