Comparing Facebook to a Nazi bar is ridiculous.
Facebook, just like all social media companies, has continually used the overton window as its standard for acceptable content. When political leanings shift, the way the company polices content on its platform, chooses what topics to boost or bury, and decides what topics to promote as part of its corporate culture changes.
It is by its very nature the thing that maximizes the political acceptableness of content for advertisers to appear next to. Most people joined Facebook when the political climate was nowhere near as right-wing as it is now, so it's not like they walked in, saw a sign that said "We're Nazis" and went "okay, this is fine."
The fact they're changing their hateful conduct policy now is what's turning them into the Nazi bar, they weren't always that way. (and yes, I'm aware Facebook and Zuck did tons of horrible shit in the past, but as a platform it wasn't anywhere near the level of terrible it will be now, nor did it have anywhere near Nazi levels of political leanings)
And not to mention how the network effect kind of changes this from "Nazi Bar" to "Nazi City" because it has a much more difficult process to escape due to it quite literally holding you and all your friends, family, photos, and videos hostage. There's less of a choice when it comes to leaving platforms that ensnare you with network effects than there is to simply leave a bar.
Who exactly? At present I'm wholly unaware of anybody on the FB board who I'd call a Nazi.
I'm genuinely asking by the way, that isn't meant to be some kind of rebuttal.
However, I would again note the fact that any current board members were likely not on the board when many Facebook users joined, (and the lock-in they experience keeps them there) and even if they were, what kind of person is ever aware of individual corporate board members?
Extrapolating that back out to your Nazi bar analogy, that would be like if you went into a bar, the people in there were your friends and family, the workers at the front were normal people, but the person who owned the LLC behind the bar was a Nazi. In that case, to "be astonished at the fascist rhetoric of the Nazi bar" isn't exactly unexpected!