More passive aggression.

I can't say for certain but I don't believe I have seen any evidence of 'hate' towards our new goalkeeper. But perhaps you are taking the words "haters hating even more" a little too literally. Personally I viewed it as him commenting that some people are all too quick to criticise, after a (PSF) game or two.

If taken literally then yes overly dramatic. If so, he joins a long long list, and this is just a mild example.
Maybe it was heat of the moment? Or he's fed up of what he sees as unnecessary negativity. I don't know, you will have to ask him/her.