You say, '"Classy" in this case doesn't mean "class." Some people are turned off by vulgar language.' Your two statements seem to contradict each other; the first one is incorrect, and the second one is correct. Perhaps you do not know what the word "vulgar" means; it means "of the common people", that is to say, the lower class.
Despite the pedantic definitions of the words, the point the commenter was trying to make wasn't about class distinctions, it was that they were perceiving it to be offensive.
The reason they perceive it to be offensive is that they are unconsciously enacting a dynamic of class domination that they cannot even question due to their lack of awareness, as further explained in https://news.ycombinator.com/item?id=22551881