Well, without knowing what was said is hard to "judge", in special with today's extreme sensibility. Being told you are doing something the wrong way is the ultimate insult. And by the way, being blunt is not the same as being rude so:

"You are doing it wrong, never use a single target rotation with 3 enemies or more" is not the equivalent of "OMG YOU XXXX XXXX XXXX XXXX XXXX XXXX !!!!!1111"