I'm amused by the credit given to native speakers. We can say, "I've never heard such a thing," or "I'd say it this way," but that doesn't mean we know what's "correct."
For example, when I say, "Just between you and me, I think she's great," people from the next register are horrified. "NO, you mean "between you and I!" In other words, what we say and what sounds "right" to us are not necessarily "correct."
Concerning the present issue, whether a compound subject with "or" as a conjunction takes a singular or plural verb, I honestly have no idea. You can't solve questions of "what's accepted" by applying logic.