Ok, so... you're good at knowing several languages, not only your native. That's commendable. But still, not knowing foreign language is not a reason to mock on a person.
I don't even think my English is particularly good, actually.
I'm incline to stick with a poor variety of words and way too often I borrow sentence structures from my native language.
I just found a bit funny that his particular brand of broken English was so immediately recognizable as Russian that I could hear it in my head while reading.
It was an innocent jab, anyway. Nothing to get too defensive about.