Bob Gale is the only reason the footage has never been released and why so little was finally released. He felt bad about Stoltz being fired and didn't want him to suffer any shame from any of his cut footage being seen, as it would instantly be compared against Michael J. Fox's performance.
Also, from what I've heard from those who have already seen the Blu-Rays, that 1:15 segment on Stoltz is all the footage of him you get to see.
"I assure you, whatever the others promise to do, when it comes to the showdown, they won't be there."