I don't think all uses are wrong. Your examples have a different meaning- the second implies that it was impossible for him to have known, which is a usage I'm OK with. However, many uses are not about different meanings. Where it is the standard meaning with a non-standard form, then there has to be a call made on the issue. In the UK, the usage is fairly minor, so it wouldn't really come across as a regionlism to most people. In the States, it may well be different.
