All Trump did is reflect back the “judgment” accusation that Cruz made against him.
The potential problem for Cruz is that he chose to criticize Trump with something that Cruz himself is vulnerable on.
I see it as something else. Trump's campaign is all about telling it like it is and making all US citizens part of the discussion. That's why it's huge rallies instead of closed door meetings.
Cruz made his statements behind closed doors to deep pocket donors. It was arrogant to think that secret meetings can be kept secret any more. And it was sneaky and old-school politics to discuss any sort of strategy with those donors. It implies an obligation to reward them for their loyalty. That maneuver played into the suspicions a lot of us have had (particularly since the first TPA vote) that Cruz is really part of the game.