Way to jump to conclusions.
While Mr. White Knight's choice of words, describing her as pitiful, was very poor (insert Joker from The Dark Knight meme here), he wasn't necessarily referring to her being a lesbian, but probably to her being ostracized and bullied – in other words: her suffering.
Honestly, in this case, no. Considering that he's addressing the bullies, the way I see it, the argument is clearly not that she's pitiful because she's being bullied by them, but that the reason they shouldn't bully her is because "she's so pitiful" - and the one thing that makes her so pitiful in the eyes of the bigots where she lives, including her family, is her being gay.