If Zuckerberg were to make Facebook politically active, it would probably be his personal views that they pushed. Why would it be anything else?
Liberal: "Stop trying to push your views on us, let people decide for themselves whether they want to be gay."
Conservative: "You are also pushing your views, and the fact that gay marriage is allowed is a result of that. By allowing gay marriage, you are forcing your views on everyone."
So, that's clearly wrong, because as smart as it sounds to say things like "the null policy is a policy," being permissive is actually possible to distinguish from any of the particular ways one could be restrictive.
> By allowing gay marriage, you are forcing your views on everyone
This is a straw man. People don't choose to be gay, and conservatives are depriving people of their rights for something they can't choose. Allowing individuals the right of self determination is nowhere near allowing a sitting president to incite violence against American citizens.
In any case, it doesn't even matter whether that example has happened in a debate before. It's simply meant to illustrate the error in failing to distinguish between liberality and restrictivism.
The difference between same–sex marriage and what Trump is doing is that same–sex marriage affects no one except for those getting married. No one is being forced to have a same–sex marriage or go to a same–sex wedding. "Forcing your views on us" means "we don't want to live in a society where this is permitted, even if I am never personally affected by it."
Trump, on the other hand, has posted propaganda about voter suppression and incited violence. This absolutely affects other people. It's not neutral to unaffiliated parties at all — how many protesters will be hurt because Trump has openly called for violence against them?
On the other hand, with no transparency, it's hard to know what kind of censorship and filtering already goes on. If Facebook removes content offensive to advertisers, why not remove content offensive to real people?