Interesting situation - if Goodell had not taken the appeal, he would pretty much be admitting that he cannot be objective in any appeal situation and setting serious precedent for every player to demand an 'independent arbitrator'. But having stepped in, he is in an absolute no win situation - anything short of him reducing the penalty to the $50,000 refusal to turn over the phone fine with no suspension and a basic admission that the Wells report was a hatchet job on top of general NFL incompetence at the AFC championship game, will result in Brady taking this to a court to force a neutral arbitrator or a court ruling. And if he does cave to that extent he looks a complete incompetent, and the league offices look even worse than they do currently, and instead of having p'ed off one owner and franchise he will have pe'd off most of the other 31.
And any court or independent arbitrator is going to look at the Wells report and the rebuttal and toss the whole thing out. The science added to the completely inadequate equipment and operators of that equipment just doesn't stand up.