Yes it is and no it’s not.
Yes they are and saying “I don’t like racists” is a different kettle of fish because literally everyone, including racists themselves, know why people don’t like them. Same as people doing the whole “jet fuel can’t melt steel beams” thing. They know people think they’re nutty conspiracy theorists. They’re asking to be a dick and push their own weird agenda, not because they genuinely want a discussion/better understanding of the matter.
I don’t agree it’s entirely reasonable, for the reasons I’ve given a number of times already now.
It doesn’t really matter whether you think it’s relevant to the comic or not, because we’re having this discussion in the year 2022 about what the term “sealioning” means now, and pointing out that, on its face, the comic doesn’t actually represent the concept as we understand it.
Even back at the height of gamergate, everyone - including the gamergaters themselves - knew for the most part that they weren’t being genuinely sincere. The early stuff about “ethics in games journalism” (and there was, IMO, a kernel of validity there) was very quickly done away with in favour of the awful shitshow it became.
Basically, I suggest the comic here is a victim of the Death Of The Author concept - regardless of what the author intended to say, on its own merits (ie, without the “gamergate” context, which is ancient history to most people now) it’s a comic about Entity A overhearing Entities B & C talking shit about them in public for no reason, asking quite reasonably for an explanation, getting an eye-roll in response, pressing the issue further politely, still being denied any answer at all relating to the question, and then (which is where the humour comes in) following them into their home and pestering them in unlikely locations like their bedroom and the breakfast table.
It’s a classic “Taking something too far” joke. There is no way for the reader to know why the woman doesn’t like sealions. Sealions are not something most people have negative feelings towards IRL. There was, at the time, no memetic or cultural negative baggage attached to sealions. That’s why we, as readers, aren’t assuming insincerity on the sealion’s part - there’s no reason, externally or within the comic - to indicate we should, and metagaming it to say “Oh, it’s actually about gamergate” still doesn’t change the fact that even back then, the insincerity was a part of that behaviour and it’s not being demonstrated in the comic.