I justify it the same way as with anyone else. They can do whatever they want with regard to speech on their platforms (i.e. resources) in the same way that you’re allowed to control the use of your resources in making speech. If nobody else gets rights to your resources, you don’t get a right to anybody else’s either. There’s literally nothing difficult to understand about that. Same rules apply to you, me, Musk, Cook, Burger King, Hobby Lobby, and a bum on the street. You’re entitled only to what you own and what somebody else may decide to allow you do with what they own. If that is nothing, then tough.