The rationale I received was, that by default, since the animals were being ranched, they fell under The Husbandry Act even though these animals aren't expressly described. In short, hunting these boars was essentially the same as hunting a stray cow, horse, pig, etc.
In the larger picture, I think what they were trying to avoid was mass hunting of those boars that became free ----- I guess they figured that there would be a mass of crazy people just out to shoot these boars and not harvest the meat. I can't say this wouldn't happen, but to my knowledge, I don't think the RCMP did enough to control what is now a problem. If I understand correctly, the huffing & puffing of the RCMP on this matter worked; I don't recall anyone being formally charged despite knowing full well that a few were harvested.