I think I understand where you're coming from on this, but I'm not sure it's "ridiculous", and it's certainly not "disrespectful" of anyone (except Karens).
It's just what happens: once *some* people start using "Karen" in a non-racial context, then *other* people see it in that context for the first time, and naturally enough they have no idea it had a racial context originally.
So *they* start using without a racial context, and they're not being "ridiculous" in doing so - they're just using the term, very naturally, with what seems to them to be its meaning.
And so more and more people see it without the racial context, and understand and use it that way...
Come back in three or five years and "Karen" (if we're still using the term at all) might have absolutely no connection to race at all!