https://nypost.com/2021/07/15/white-house-flagging-posts-for-facebook-to-censor-due-to-covid-19-misinformation/

If this dosen't prove that the "they are private companies" argument is complete and total bullshit I don't know what is. Yes they are technically private companies but they are private companies acting on behalf of a corrupt government which is corporatism aka fascism.

7535307 Because only they know what the truth is...

7535577
Lol. Nice comic.

What is freedom of speech then? Whoever is in power says it is?

Your 'free'... as you don't say somethings I don't like, I guess.

7535632
It's a sarcastic riff on this one:

They believe that "free speech" is only what's covered in the US constitution, not a broader concept. Anything other than the US government directly threatening you is fine according to them.