Despite the attempt to change his delivery, the primary knock against Henson has never involved his measurables. He's a superior athlete who is built to prototypical QB specifications.
The knock against him involves the mental game. Inexperience. Confidence. Decision making. And reading between Parcells' lines, mental toughness: the ability to respond while under fire.
My guess is that Parcells has real doubts about Henson's mental game, that Parcells talks about these doubts (knowing that the comments put Henson under extra pressure), and is waiting to see how Henson responds.
Parcells often just says what he thinks and then sees what happens. Some people call this "mind games."
And going by Parcells' comments, it seems to me that he isn't at all hung up on the "Romo or Henson, who is better?" question. Parcells is evaluating each on their own merits.
Right now, because of Romo's longevity and contract situation, Parcells has to determine what kind of future Romo is likely to have in this league and whether the Cowboys should keep him around.
Henson is on the backburner because the Cowboys don't have to make a decision about him this year. This is probably a good thing for Henson. He gets more time and reps before his test comes.....