There's a grand tradition of distinguished physicists approaching retirement deciding to solve the problems of philosophy. The general response of philosophers to there ideas is a long the lines of "well that was a good solution when Aristotle/Hume/Kant/Russel first proposed it".
@You aint sin me, roit
"As for Hawking's physical limitations... neither of us know, but maybe he spends a lot of time just "thinking"."
That's the problem: Philosophy is done by thinking but you can no more do real philosophy by "just thinking" than you can do real science without peer review. Without the social structures of science even the greatest genius will end up a crank the way Newton and Tesla did. When the genius is a scientist trying to do philosophy the problem is only exacerbated.
As for philosophers not understanding science: It's pretty common for academic philosophers to have degrees in other disciplines. Unsurprisingly, physics is a favourite in that respect.