Maybe if he'd seen Rings of Power. In general though, not really. The fact that they have been enduring and inspired so many other things fulfills what he wanted, to create a mythology. Mythology endures, inspires and teaches.
Dude died in '73, before fandom was even a thing really. Star Wars didn't come out till '77. I don't think any adults were doing fandom type stuff for Buck Rogers or Captain Nemo at the time.
According to the LoTR making-of videos they had on the directors cut, he was horrified that people were doing cosplay, graffiti of lines from the books and doing hobbit-inspired weddings.