Sure, but whether the choice has any political content depends on whether YT considers themselves publishers or infrastructure. If they just want to be the world's video hosting site then they're not taking any political stance by staying out of it and just hosting what people upload.

They don't have to decide anything like that. They could prohibit cat videos for no reason tomorrow, and suffer whatever the consequences of that are.

They have chosen to try to stop ISIS recruitment by videos hosted on their site. That is their prerogative.