As someone who isn't from the US and doesn't speak English as my first language, it's not the matter of "grammar". If he is sincere about the communication he is trying to establish, he'd have tried a lot harder. I respect him as much as how much he respects me.
He obviously has no problem with the language. Trust me, I have a ton of friend who do, and there's a huge difference.
Hey cow as the English professor you are shouldn't be "Trust me, I have a ton of FRIENDS. who do..." you are referring to more than one friend that it's plural.