McKesson chose to interpret it as an open death threat, it obviously wasn't but nobody was going to call him on it, and it got Johnson booted off Twitter. I see your point, but that wasn't how McKesson and his fans used it.
Regarding the Spike Lee thing, I'd say he got a pass because he's a celebrity, but who knows. This is kind of my point. You have to piece together pattern out of Johnson's activity on and off Twitter to decide that maybe he was trying to get deray killed by paying people for his home address. On the other hand spike lee directly tweeted "here's george zimmerman's address, share this as much as you can" and nothing happened to him at all. Twitter was aware of it, because many, many people made them aware of it, and they pay special attention to their celebrity accounts. it didn't happen off twitter, it happened on twitter. and it wasn't tangential to some other threat, it was a direct threat. on twitter. tons of people reported it. I just can't hurdle this one. they let it happen and they didn't care.
the commonality across these is that in the best circumstances you're probably a scummy person if you do that, Johnson or Lee, but it's extra terrible when people just tweet addressed with death exhortations and they didn't even know or care if it was correct info. johnson was pretty scummy but his point was made, if you're the new york times nobody seriously is going to hold you to that. if you're spike lee, nobody is seriously going to hold you to that. if you're charles johnson, you're booted off twitter, lose your internet hosting and two dozen newspapers write stories about you.
2. it's not actually that vague, you could take what I said and watch and see if you can observe it. I gave you enough information if you were truly interested. You're not obligated to believe me or do it, of course, I was just sharing my experience. I kind of have a problem proving this is intentional, because I don't run twitter. i used to live close by what I suspected was a crack house once, people were always coming and going, and doing crack outside. Maybe the police could prove it, I can't. but I can tell you what I saw.
You are very correct that it's hard to tell what is intentional and what is not on the part of twitter. I see a lot of bogus claims of shadowbanning where it's really just that twitter is eventually-consistent, and sometimes you try to look at data from one location and its there, someone in another country can see it, though. Roach-motel hashtags, some are more obvious than others, and some are just legitimate misspellings that catch on because that's what everybody types. Example, for a while podestaleaks was autocompleting as podestraleaks. On the other hand, SpiritCooking trended for almost 24 hours before it stopped autocompleting and was replaced with spiritualcooking, which roach-moteled you into ancient sparse tweets about cooking. I can't prove anything, but come on. As far as straight up suppressing trending tweets, it's not even arguable. things trend, then abruptly stop autocompleting and drop off the site globally. they already do this to prevent spam, and it's obvious they do it to shut up some hashtags.
3. Have we not yet gotten to the point where that odious xkcd cartoon has been thoroughly debunked? Freedom of speech goes far beyond being a simple ban on things you can or cannot say or else you will be punished by some authority.
I am sorry if this is long and rambling, I wanted to say what I've been seeing because I am not the only one who has made these observations, and this is a particularly good place I could say it and people with more ability than me to investigate this might see it.