Gutted.
Have had a relative deal with a similar diagnosis. It's all about palliative care at this point, I hope he has all the care and comfort he needs.
My George story, which is a similar story to many of your stories, came back at Dragon Con about 6 years ago. George (in his trademark Hawaiian shirt) was late getting back to his table after a lunch break and I was there in Artist Alley (Room) waiting for him. About 10 minutes late he came scampering in the door getting corralled by his handler, plops down in his seat and starts apologizing for being late (no one was mad) and starts just extoling how much fun he has at this con and talking about all the amazing cosplayers he's run into and how it's impossible for them to expect him to stay at his seat when there's "SO MUCH AMAZING GOING ON JUST OUTSIDE THAT DOOR!"
It was a joy to see someone loving the community he'd help create and foster through his work.
It was totally worth lugging my COIE and JLA/Avengers Absolutes through the convention to get them signed by George.