I don't understand why 'the Crown' would decide there were no grounds for charges - it sounds like a straightforward case of assault.
Nothing is straightforward once you enter the courtroom. First you have to consider if there was an "assault". Are there reliable witnesses? Was there the intent for harm? Was there harm? Harm also has to be tangible, such as injury. Hurt feelings, humiliation and embarassment don't constitute harm.
The bar is set quite high for criminal offenses, and rightly so, and it would be quite conceivable that a charge would be defended vigorously. What is the chance of a conviction? Hair does grow back, so is it in the best interest of justice to tie up the criminal courts for this matter when there are more pressing cases pending. Thunder Bay is a port city with its share of contaband, Mafiosi and other crime groups. These would be some of the things the Crown would have to consider before laying charges.
I don't mean to sound insensitive, but the courts aren't meant to be touchy feely, nor do they act on the cheap, this is the reality. The Crown doesn't try cases on the off chance they might win it, they are in it to win it.
Even a civil case, where the bar is set lower, would be a tough one, again because harm has to be proven. I would think the only recourse at this time is to fire her butt and either suspend or revoke any professional tickets she may hold.