No, it's not. It's asking you to simply not post nasty stuff. It doesn't mean you have to embrace other cultures, sexualities or whatnot. It doeesn't even mean you have to like them. It just means keep any nasty comments about such things to yourself (or go say it elsewhere).
It's a really sad time for humanity if common courtesy is now considered "left-wing".
It's a really sad time for humanity if common courtesy is now considered "left-wing".