I'll break down my thoughts into several related blurbs. This is a complicated topic, so I'll be as direct and intentional as I can be with the knowledge I have.
I do not agree that propaganda should be freely distributed by people or governments outside of the US. Propaganda is a weapon and should be treated as such. It needs effective countermeasures and if that means completely blocking the operation of a foreign company, so be it.
I do agree that data protection laws need to be expanded which will help limit what any company, foreign or domestic, can collect about individuals. That is a no-brainer.
Data protection laws are great, but we have seen time and time again that many companies give zero fucks and it's still more profitable to pay any associated fines while still selling or misusing data. Foreign governments really don't give a fuck what our laws are, either.
I am not a lawyer, but it seems Lamont v. Postmaster General needs to be revised. A letter is not a cellphone. Cellphones can send, as well as receive information. Your data can be used to instantly craft propaganda specific to an individual. That is not good.
Normally, I am a fairly staunch backer of the EFF, but I disagree with their stance on this one. Lamont v. Postmaster General simply doesn't take into account modern technology.
However, I have no problems with US citizens spreading messages to other US citizens, regardless of the subject, and as long as it's not for the express purpose of restricting my personal rights in an extreme way. (A example of communication that should be restricted: US citizen-to-US citizen communication in regards to planning a coordinated terror attack would possibly be in direct violation of my rights or the rights of any intended victims so that wouldn't be acceptable, IMHO.)