Rest in Peace to a man who took the forum as seriously as it should be taken, and a very nice person indeed.
An entirely non-systematic review of Pittsburgh area obituaries has yet to confirm this. That said, my recollection of Grumps' age and appearance are vague, so you never know. If this is true, that is truly our loss. Best to his wife and family.
I found one that more or less seems an exact match based on my convos with him, but not going to share here so as not to doxx him/his family or potentially mislead if it isn't him.
I also found an obituary that seems to be a match.