Oh god are you really bringing up a “women do it to” point completely unprompted?

No. Merely stating that women aren't as fragile with a need to be protected as discussion like these often make them seem, e.g., "advancing on her was grooming by default because all people of that age are vulnerable". Seinfeld advanced, Shoshanna consented, and so did the parents. There was no vulnerability being exploited here. If it sounded like whataboutism then I should have phrased it better.

As for “being attracted to fertility” and whatever…yea that’s not it, chief. Maybe I’m of the group that doesn’t see it that way but I’m 30 and I see someone ~25 and under and I see a child, not someone I should be sexually attracted to. Certainly not someone who I’d actually give that kind of attention to. I’m more than monkey brain, and maybe most people aren’t but we trust them to have jobs and shit so they should be able to handle this, too.

Perhaps this is the crux of the matter, more people than you'd like have monkey brains. Have you looked at human behaviour in general? In comparison Jerry and Shoshanna having been a thing at their ages is a triviality compared to the actually unethical harmful things we do as a society. And just to be sure, this isn't a whataboutism again, because considering the quote mentioning her parents, there was no harm done.

Anyway, to bring it all back to my main point, it not being unethical doesn't mean everyone should intentionally start dating younger people, but merely that calling Seinfeld a paedophile is an irresponsible and ironically childish unconstructive thing to do. Just like him saying “'Free Palestine' are worse than the Ku Klux Klan”.