Think about the number of words you have written on this particular subject. I’m not saying it automatically makes you a weirdo to think so long and hard about this but… I wouldn’t want to hang out with you.
If you were falsely accused of rape or murder, would you want a lawyer that analyzes your case long and meticulously or a zero-attention-span illiterate straight from Idiocracy that sifts TikTok's "Ow-My-Ballz" videos all day?
Thinking long and deeply about oftentimes uncomfortable subjects or ethical dilemmas is why becoming a lawyer, doctor, judge, et cetera, is difficult, and accusing a person over the Internet is not. The latter unfortunately requires Brandolini's law to refute: “The amount of energy needed to refute bullshit is an order of magnitude bigger than that needed to produce it.”
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.
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”.