He subscribes to a view that is in the minority.
Sure he does, which as already pointed out doesn't automatically make him wrong.
The consensus amongst almost all Shakespeare scholars is that he wrote the plays. All of the historical evidence says he did
The anti-Stratfordians, as they're known, disagree with this otherwise they would have no case to make, which they do.
and there is no contemporary record of anybody disputing the authorship.
This is perilously close to the 'absence of evidence' thing - and Hope in #17 disagrees with you, so you'd better take it up with him (
"His authorship was being questioned even whilst he was alive").
I'm not an expert but I don't see any reason to dispute the consensus view amongst the scholars.
I'm not an expert either - nor, as you point out, is Sir Derek, nor is Mark Rylance. Still, it's easy enough to bone up on if it takes your fancy, surely? The anti-Stratfordians write books and make documentaries and give lectures and suchlike.