That sounds a lot like "censor foreign media and domestic anti-regime media". I'm of the opinion that if foreigners can convince me and my countrymen of something just by posting, we probably didn't really need the convincing anyway. Even if it turns out my position on something was changed 180 degrees by foreign posters (even Chinese intelligence employing cutting edge propaganda AI, or whatever bogeyman you want to employ), then: Fine. Whatever. Persuasion of citizens in a democracy is just how a free society works.