Nah, Silent is right. It's not exactly derogatory, but the point of a facebook/twitter hack like that is that you write something embarrassing. The implication is that Szczesny would be embarrassed if everyone thought he was gay.
On its own, obviously, you'd have to be a right delicate flower to be offended. But it is indicative of the sort of light-hearted banter which nonetheless wouldn't exactly encourage a closeted gay player to come out to the dressing room. It's not about thinking that individuals are actually going to be homophobic to you, but about feeling that the culture sees being gay is something to be laughed at.