It's all just speculation since it's basically only a game mecanic. But since some maneuver are red on some ship while being white or even green on others, I don't see why it would be impossible that the Tie Defender is able to do a white K-turn, especially if it's as maneuvrable as some people claim it to be (no expert on the EU so I really don't know).
Also, there is a pilot skill (adrenaline rush) that allow you to do a red maneuver without gaining a stress token once per game, so it is already possible to do a white k-turn. I don't see why it would be impossible to allow it on an especially maneuvrable ship. Even with that maneuver, I would still consider the E-Wing a better ship with all the possibilities.
Just my opinion.