The director also tweeted, "I am not making any money on it and I refuse to accept any from anyone." Well, everyone ought to know by now that that argument isn't going to fly if you put a copy of The Avengers on your personal home page. It's not obvious why that defense should work any better if you've violated someone's copyright by using their characters without permission, instead of just copying their movie.
Some sound arguments here. And also why it's so hard for those of us who have to play by the rules of copyright laws to create truly original pieces. But yet, we do.