My understanding is that there is already court precedent that the government can’t do this (use private companies to do their censorship even if it’s not strictly guaranteed to happen).
I would be pretty surprised if this was true but 3rd Party Doctrine is in good standing in 99% of cases.
Edit: Yeah, it appears this is not true at all. The government of course cannot coerce a private company to do this (which is obvious since that'd be tantamount to the government itself doing the censorship), but they absolutely can request it. https://reason.com/volokh/2021/07/19/when-government-urges-p...