Well of course when he made the flash he sort of foresaw that the fans of pewdiepie would react like this. Maybe he wanted that reaction. The fans reactions was immature, moronic and shows how insecure they are if someone make a flash bashing a guy they like and this is the response they give back. But of course people will never learn and there will always be fans like this, not just pewdiepie.
As for whatever Speedo was wrong to make the flash in the first place I would say no. He is entitled to whatever he wants to, and although I myself didn't find the flash very funny (because newgrounds is already filled with half assed parody flashes) I don't think it really something you should get upset about. It is one guy that made a flash that portrays a guy that you may or may not like as an unfunny idiot.
So my point is, stupid fans will always be stupid. And if someone bash the guy they like they will go out of their way to make themselves heard and only give people that didn't like the guy or his fanbase in the first place more reason to hate them.