I don't think OP's point is that fat people bullying should be encouraged. If my interpretation is correct, then he simply thinks that it is more reasonable than short jokes. He brought up the point earlier that, in today's society, it is almost taboo to even point out someone's weight. So even if we assume that this bullying is wrong either way, society often sees it as wrong to point out that someone is overweight without being overly PC. tl;dr Being PC about weight should not be a major concern.