According to a google search he never admitted to this crime in his life, the admission is only posthumous.
(thelemmy.club)
Well I don't know about Kiss controversies or such, I don't doubt that and if that's true, he needs to rot in hell.
But, this memorial stone is from this guy who has a normal Headstone as well (go to the last pic).
https://www.findagrave.com/memorial/246048914/eugene_marion-simmers
And if you check out the tour dates for the "Gene Simmons Band" you can still go see the living genocidal bigot.