Nader's public defender doesn't have the time or the energy to play 5-D chess and set the stage so Chantal can be raked over the coals. Even if she could somehow serve a purpose toward exonerating Nader, or if there was any legal merit to the idea that getting her on the stand could play into punishing her for the false charges she filed, no one would do it because Chantal is clinically insane, a proven liar and never thinks of consequences when she is angry, and she is very angry at the moment. If a defense attorney knows that at any moment something could come out of your mouth that could destroy the defendant, ain't no way that person is going to be called to give testimony. Unless the prosecution is calling her to court, Nader is lying, and even the prosecution would be unwilling to deal with her since her very presence there would emphasize the fact that some women do, in fact, lie about abuse.
And I don't think the specter of being summoned to court influenced Chantal's decision to go to the Middle East. Chantal is before all other things a lazy glutton and she would not have wasted food money and energy hauling herself to Kuwait were there not a lot more going into it than just avoiding court. If she wanted to evade such a thing she would fake an illness to go to the ER hours before she was to appear. Or fake a psych emerg issue and land herself in a 72 hour hold (or however things like that work in Canada).
So my money is on Nader lying about trying to summon Chantal to court. We'll see.