If they successfully do that then isn't that in fact the exact democracy working as it should? If you turn it around, you are endorsing the US government cutting off free speech specifically to manipulate people's voting opinions towards its own perception of what is "good". That seems almost exactly the opposite of the spirit of the constitution.

Perhaps an appropriate response here would be to detect this manipulation and highlight and educate people about it. Possibly create regulation to outlaw specific types of highly problematic aspects of it. But I find it hard to simultaneously accept that it's both so subtle as to be undetectable and unregulatable and yet so terrible it warrants arbitrary restraint of free speech.