Twitter is all in public. I don't need a twitter account to be able to read posts from any twitter account. [1][2]

Facebook is private. Given I have no account I can't see any posts on facebook at all. Facebook can target the mentally unstable with incendiary, racist, sexist, violent and awful content /in/ /secret/. Whether by ads or through groups or similar. You have no idea what privately broadcasted communication is happening there at all. You probably have no idea of the nature of something as simple as political advertisements targeting those of a different political persuasion. None at all. It's dark to all of us.

These are two quite different ways of broadcasting. You may wish to regulate communication on both or one but not the other or neither. Unless it's neither you favour it seems unlikely that the same regulation and enforcement is appropriate for each of these things.

[1] Locked accounts on twitter don't appear to be a significantly used thing. Will obviously update that opinion in the light of better information, eg if it turns out that violent groups coordinate and recruit using locked twitter accounts. I don't believe much like that to be happening at the moment.

[2] Without anything more than a browser you can read for example, Glenn Greenwald's latest twitter post at time of writing. https://twitter.com/ggreenwald/status/1349514741358669824 Then agree, disagree, decide if he's a russian spy or a principled journalist focused on social justice, brilliant or a moron, or just right or wrong on just this one thing or you may decline to form a view. It's not secret. It's not communication happening behind your back that you don't know exists. (This particular post is also obviously not incitement to violence).