Time/place/manner restrictions typically apply to public property. These are private websites.
While the court has once or twice extended protections to people using private property as a public forum, to my knowledge they have never done so with time/place/manner restrictions.
These are private websites accessible over the public internet, to be clear. Also, there are known relationships between the intelligence community and the big platforms, lets not pretend they have free reign.
Should/do we allow foreign propaganda radio stations? If we accept that the government can (and very much does) impose itself on content platforms for "national security", what exactly is the difference between deliberately insidious information warfare, and collateral damage from market incentives?
I agree that its better to find solutions that involve protections instead of restrictions though. I think it means forced decoupling of indices/curation from advertising. This would make advertising funded addiction feeds compete with paid feed applications.
"No loud music between 10pm and 7am." That's on private property when it can be heard by others. Laws have all kind of restrictions on the time/place/manner of self-expression when what is being expressed has a negative effect on others. What you can't do is have laws that would say loud opera after 10pm is OK but loud Country & Western isn't.