The free speech absolutists would have been more convincing had they been as up-in-arms about the banning of ISIS or ISIS-affiliated accounts over the last several years. This happened by the hundreds-of-thousands.
For better or worse foreign and domestic terrorist speech is treated separately. If ISIS was a domestic terrorist organization afaik they would have 1A rights.
What's the connection to the first amendment? Did the government dictate bans? I saw very little concern from the "free speech" crowd about the government's ability to censor US publishers from publishing content by foreign authors.
There's been plenty of concern about that. See the Mehanna case from a few years back. Also, the USG was giving Twitter shit about having terrorist content on their site for years.