The problem with the original comic, is if you replace the her statement about Sea Lions, with any group (be it by gender, sexuality, race or religion) then the woman is clearly making a bigoted statement, surely members of that group deserve some justification as to why she is being exclusionary to them.
Also Sea-Lioning is generally referred to people persistently asking someone to defend their bigoted stance, when like in the comic they never do. However unlike the comic, generally the Sea Lion sticks to the thread or topic that the person made their bigoted statement (but yeah will keep asking why that person hold bigoted beliefs), it's not like they can follow them home or off the internet.
Maybe that comic would make sense if there were earlier comics where we saw the Sea Lion being a complete dick towards her, that might explain her and justify her opinion of them, and provide a wider context for this comic. But still unless all Sea Lions are always being dicks in earlier comic then she is still judging a whole group of marine mammals on the actions of one... sounds a little racist (speciesist), yet we are meant to believe she's the victim.