I didn't suggest they're always wrong, or that all of them are wrong, or that some of them won't have done any checks on what they're teaching. I said that teachers will be wrong about things. That only means they're fallible and don't get things right all the time.

If any teacher, or literally anyone else, is offended by the suggestion that they're human and could be wrong sometimes then I think I'm OK with offending them. If you think you're perfect and will never be wrong then frankly you deserve to be offended as often as possible.