I honestly think there is no hidden meaning in Gary's choices of music or pictures. In reading the guestbook, it appears he started feeling bad, called his son to take him to the hospital, and apparently passed before he got there. I can't say he never had an ongoing condition, but I think he wasn't ill, it just happened. The suddenness of it is what makes it all the more shocking. Literally here one minute, and gone the next. He had 2 windows open, one to 7F and one to 8F. It's put many of us in a funk, I notice his absence constantly. To quote Data:
As I experience certain sensory input patterns, my mental pathways become accustomed to them. The input is eventually anticipated, and even missed when absent.
I won't become morose as Gary was a humorous guy, but it has been...difficult.