Second, the first amendment only applies to US citizens and those on US soil. So, as pointed out, American's have the right to seek out such information, but those oversees have no such right to have it disseminated here. Someone in the US can take the information and broadcast it on their behalf, which is how it happens now, but the notion that foreign agents have a right to create and disseminate whatever information they like is patently false.
How else are they going to disseminate media in the United States? They certainly could disseminate it via the Internet, but then the US would have no ability to block the information except via a Great Firewall, which the US does not have.
It's a distinction without a difference. RT is a Russian Government-owned propaganda network, with an American subsidiary, which operates in the US and broadcasts soft propaganda all day long.