The same as the inventor of Pacman feels for teenagers popping little white pills while listening to repeatitive computer music.

The fact that first person shooters are played by hundreds of millions all over the world, but mass shootings are 99% a US thing (which much predated first person shooters, e.g. "I don't like Mondays") should answer the question...

Almost certainly not, I'd hope he's too smart to see a link between FPS games and these events.