Michael Bay actually took time out of his day from being an unimaginative hack to comment on the leak:
The leaked script for Ninja Turtles that different sites continue to comment on was written well before I, or anyone at Platinum Dunes, was involved with the project.
That script saw the shredder a long time ago.
This is tired, old news -- Wait for the movie!
First off, this is even more confirmation that the script is the real deal.
Secondly, Michael Bay and Platinum Dunes were announced to produce the reboot in May 2010; the script was dated in January 2012. So, either the date was wrong, or Michael Bay is a liar. I'll go with the second theory.
Third, if they don't plan on working off of this draft, it still means that the same two guys who wrote the script are still working on the film. How is this progress?
"Wait for the movie!" No, Michael. We don't want to wait for the movie. Because by then, it'll have been too late.