Earlier quoted context omitted.
Even if you know for certain that someone is an anti-vaxxer, disregarding their opinion/question by accusing them of sealioning is a fallacy. Someone is not a "bad-faith" actor for asking precisely the questions that are hard to answer, even if they're using those questions to support a wrong idea. If you don't have time to answer their questions, don't answer them. If you do have time, you have a good opportunity to…
> Even if you know for certain that someone is an anti-vaxxer, disregarding their opinion/question by accusing them of sealioning is a fallacy. 1. Labeling someone a "sealion" doesn't even hinge on their opinion. You seem to have missed the entire concept, and instead interpreted it as a generic dismissive. 2. Uh, you don't get to just call something a "fallacy" because you don't like it (though many others are doing…
If you look at the original comic[1], the sea lion follows the couple around in public, into their house, and even into their bedroom, without permission; that is what makes the sea lion's behavior bad (criminal, in fact). However, "sealioning" in practice refers to people responding to public internet comments with other public internet comments. To treat the latter like the former is dishonest.
Furthermore, the sea lion is objecting to unsubstantiated criticism of his species, which is a form of bigotry. Imagine people searching Twitter for criticism of, say, their race or religion and arguing back at it. I suspect that 90+% of those who complain about "sealioning" would consider that behavior permissible and probably downright virtuous (and would add that the arguing-back need not be scrupulously polite). I'm frankly surprised that "social justice"-associated people managed to decide that objecting to speciesism was worthy of mockery. I think they just really wanted some term of disparagement for their opponents, and happily accepted this one when it appeared without analyzing it too closely.