No it's not.
We've verified the address and we verified the computer from which the posts were made.
There's not reason to think that this isn't Mr. Gross. You don't have to believe it, but try not to be too insulting.
“Washed up producer”? That's showing no class and no respect. When you have a CV like Mr. Gross', then you can pipe up about whether he's washed-up or not.
As for faith, some of us have been keeping the flame alive since the last movie came out, and we're still here.
I was rather hoping Mr. Gross would continue to post, so questions about the making on the films could be asked, but why would he if you're going to take everything he says personal.