The text of Kerry's speech has been printed (and from what I gather he has not been pressed to admit if he personally saw or participated in any of these attrocities).
Also Oliver North has been circulating a quote from the Vietnamese where they described the strength that they got from the antiwar movement.
Deliberately propagating lies (not to mention lying before Congress) is a big story and perhaps an act of treason. Axis Sally was convicted for it after WWII. It certainly provides aid and comfort to the enemy during wartime.
Hanoi Jane is the benchmark case though; if sitting on an enemy antiaircraft gun and posing for photos isn't treason, then nothing is.