A lot of people believe that she removed Bobby's choice to choose to accept it on his own (which, regardless of his future self, is completely possible. All the "Young X-Men characters have changed a lot over their time with their older selves). When someone else "outs" a gay person, it can be extremely damaging to them. But we're talking Young Jean "I'll do whatever I want" Grey here, she doesn't seem to give a shit about the term "privacy" since she has been developing her psychic powers.