Is it really appropriate to criticise the speaker for simply not knowing some subjective 'correct' way to speak?
Nope.
Something I came across not so long ago, which is related but not exactly the same: when someone mispronounces not very common words, it's likely that they've learned them by reading them not by hearing them. Given how odd English spelling can be, it's hardly surprising if people get pronunciations wrong.
I thought vehicle was pronounced veehickle until my dad told me the correct pronunciation. I'd have been about eight and reading the word off a road sign.
He thought that a street that, as a boy, he cycled past regularly was called Gipton Appricotch. He liked it but wondered how it got that name. Then one day he read Approach ?