What do you mean, "sexual predators will not play these games"? Why wouldn't they?
Tobacco addiction still fits my illustration. There are many pack-a-day type people. But they don't start like that. They start small and need more and more until they are pack-a-day types. Some may stop before they reach a pack a day. But they are still far closer to that than someone who never starts. And they still suffer many other negative effects from their use of tobacco that those who never started don't have. Additionally, tobacco is not fulfilling a perverted, evil desire the way sexual assault is. With sexual assault, the end result is far worse.
I'm not blaming rape or sexual assault on the video game. But first person shooters -> school shootings is not an apples-to-apples comparison. Most of them are in the context of war, which is different from school shootings. I would condemn a "School Shooting Simulator" game on similar grounds that I would condemn this game on. If a game contains purposeless, realistic violence, and the sole point of the game is to revel in that violence, I would say that raises red flags.
The idea that what you do for entertainment doesn't affect the rest of your life outside of that entertainment is just laughable. Pay attention to your own life, and you will see that it is true. Playing a game like this can contribute to the perverted desires that negatively affect everyone who has them, and can drive some to do terrible things. Meanwhile, what's the upside? It is fair for a platform to decide to remove porn (which is not speech) that negatively affects everyone and benefits no one. As someone who has use this platform for years, I support that decision 100%.
I think that the best option would be to refrain from committing sexual assault AND to refrain from fantasizing about it?
And if I were running a platform, I would be absolutely justified in removing content that promotes such things.