I think it is silly to talk about not buying or selling any game that JT had a hand in designing. Where does this logic end? My guess is that he probably provided feedback to other designer on other games. Why not just sell and boycott all Stern games just to be sure they're not tainted. Sell all Midway and Gottlieb games just to make sure he didn't work on other games in your collection.
How about all of the other people that worked on the game? There are probably dozens of people that had a hand in making your JT game putting as much or more creative energy into that product development; artists, musicians, other designers on the team, electrical engineers, mechanical engineers, coders, operations, accountants and labors just to name a few. It's likely that the time JT spent on his portion of the game is a fraction of the time other people spent.
And was all of JT work original? Sure, he was a major force in pinball but he was certainly influenced by others. Creatively, everyone is influenced by others. They stand on the shoulders of other giants that came before them. When I listen to podcasts with older folks in the industry, they talk about certain people starting games and then they are given to other to complete. Kanada recently interviewed a female artist who's been retired from the industry. It is amazing how inaccurate the IPDB was on games she worked on and how much work is moved around between and within the creative team(s). My point is JT is only a part of the development of each machine and we don't even know how much influence he really had on each game.
I've seen this exact situation in another hobby of mine. This is the problem with hero worship in any hobby or creative domain. We put these people up on pedestals. When the hero fall, it makes people depressed, angry and sometimes irrational.