Multiple developers have told Pocket Gamer that Apple is starting to reject games and updates from the App Store, if they use screenshots that show people holding guns, or being maimed or killed.
There’s really not that much controversy to be had here...
The App Store has parental controls and requires all apps to bear age-appropriate content ratings. While violence, etc. has always been permitted in apps, Apple has always required that all app metadata — title, description, icon, and screenshots — be kid-proof with the lowest rating.
It actually says it right there in the rules:
3.6 Apps with App icons, screenshots, and previews that do not adhere to the 4+ age rating will be rejected
The rule is old, clear, and reasonable. The problem isn't that Apple has now started rejecting apps using this rule, it's actually the usual problem of inconsistent enforcement.