Why is what? Why did I interpret this as what the author was saying? Why is censorship generally implemented in a biased way?

If the former, based on the way the article was written, I interpreted that phrase as saying that FB is worrying about censoring one side of Isreali-Palestinian, but not the equivalent views on the other side.

And that leads to the conclusion of the latter question above, which is that this is how it generally goes with censorship. We generally only want to censor opposing viewpoints, but not our own views which are often logically equivalent (because being so emotionally invested in our own viewpoints and only being able to see the world from our own vantage point does not allow us to see the opposing views as logically equivalent). That is one-sided and logically inconsistent, but is human nature.

I wasn't saying anything about what should be illegal and what should not, only that I think you misinterpreted what the author was trying to convey.