To claim that the actual semantics of a word can be defined by anything other than the behavioural tendencies of its users is, at best, highly controversial. Whatever you or I may think, "irregardless" just is a (near) synonym for "regardless"

I'm advisedly ignoring the original context, but I'm curious about the idea that your behavioral tendencies in particular (and mine) with respect to the usage of "irregardless" don't affect the actual semantics of the word. At best, it seems that "irregardless" both is and is not a synonym for "regardless"... as well as both being and not being an antonym of it.

Unless only some usages count? Perhaps there's some kind of mechanism for extrapolating coherent semantics from the jumble of conflicting usages. Is it simple majoritarianism?