Are you saying (1) "This update to the system's defenses would be circumvented by attackers using this alternative method."?
or are you saying, (2) "An easier solution is for the department of defense to inject their own commenters into the comment sections so that truth combats the noise our adversaries bombard us with."?
Replying to (1):
This suggestion of yours would involve foreign adversaries having to recruit Americans to be traitors in a way that is (A) easily tracked to their personal identity and (B) risks imprisonment.
It is true that they could try this method, but I doubt their success. Few people would betray their nation and community in such a transparent way.
That severely handicaps the efforts of our adversaries who are currently waging a war for the minds of some of our most vulnerable and unstable citizens.
Replying to (2): The DOD already does this. I know of several such operations of pretty cool levels of sophistication. I think the efforts are made with good intentions, but I think this whole effort falls short and doesnt stop the problem at the source. It also makes it so that comment sections everywhere appear "crazy" and enemy efforts still succeed from time to time at programming our citizens against the state.
A useful idiot (Russian term) programmed by an adversary to doubt the truth will often times see the government's sincere efforts to spread the truth as evidence that the government is corrupt. These idiots will seek refuge in news media ran by adversaries like RT dot com.
A useful idiot will also find themselves accused of being a foreign shill. By being accused of working for a foreign government while knowing they are just a normal citizen, these useful idiots immediately begin to believe that there are no foreign shills and that they are, in fact, all Americans who are being oppressed by a corrupt government. It is this state of "foreign programmed useful-idiocy" that renders an idiot to become a pawn to our adversaries who will then go around spreading anti-western civilization misinformation.
We should just prevent all of this outright, I think #2 is simply not enough.