Those PACs were likely already going to propagandize. It's not like they suddenly become more powerful or concentrated because the state media promoted posts that happened to align with them disappeared.
Also in some instances like foreign influence (e.g. the HK protests and surrounding state ad campaigns from which this policy ostensibly stems), there may not even be a corresponding PAC. So shutting down that advertising could be surprisingly significant.
But in the end, the effectiveness of regulation is proportional to the degree of effort avoidance or circumvention requires. I say, "Twitter: good call." Let states speak for themselves.
Nation states however have no such right. Thus the ability to bar their propaganda is much lower, as it should be.
edit: limit to bar in p2
You can't pay for votes, you can't have someone sign their vote-by-mail ballot and fill it in for them, you can't vote in-person in someone else's stead (even though it doesn't create an extra vote), and so on. There are also plenty of restrictions (at least in the text of the law) on how to handle the ballots themselves.
None of these are restrictions on the right to vote.
For example, "do not criminalize weed, because it will push incentives past a tipping point for the opening of unregulated cross-border trade routes".
Decisions are not made in a vacuum, there are always fringe effects.