Misleading
>Those same companies that have spent a decade fighting any effort to limit their users' content, and have argued vociferously in favor of the First Amendment....
>This leap between diametrically opposed positions in just a few short days has sounded its own warning alarm.
I think this statement is pretty misleading. These companies have fought against government censorship of their platforms, which is a first amendment issue - the government dictating what's allowed or not on their platforms (i.e., government censorship). But they've always had terms of service that state what type of content is disallowed and the consequences of breaking those terms, and that's well within their right to decide whether they want to ban racism, sexism, bullying, harassment, etc or even a simple as off-topic discussion.
The issue is that they've also allowed politicians - particularly Trump - to get away with posting content that would've led to a ban for any other person, all under the guise of 'the public interest'.