Or in this specific case, why would someone call these proofs (no one is saying they are wrong) AI slop if not to delegitimize all AI output?
* even pretty amazing advances like this one
Good AI output is indistinguishable from human output. The whiff you mention is the reasoning pleonasm and tautology (intended) escaping into the output and the "author" not proof-reading/editing it out.
Then it's a useless term and we should all stop using it.