> companies can speak with the police and follow their wishes regardless of the first amendment because Twitter's own protected speech allows them to block any content for any reason, whether that be "it violated our content on harassment" or "the police don't like it and we're voluntarily following their wishes".
Even if that wasn't against the First Amendment (which is a more complicated issue [1]), that wouldn't fly politically in the US. The side which likes law enforcement also currently puts emphasis on free speech, and the side which doesn't like the police wouldn't want them to be in charge of censorship.
I think a company doing that would make everyone their enemy, and generate a lot of bad PR.
[1]: For example, see https://en.m.wikipedia.org/wiki/Chilling_effect