Jack is volunteering to do just that.
He's volunteering to stay longer.
In what world do you imagine Canada has any influence whatsoever in what happens in the occupation? Ask Webgear, and he'll tell you under whose command and pleasure he proudly serves (hint: their headquarters has five symmetrical sides). I know you can twist logic like a freeway overpass, but to conclude that Canada's subservient role to the US somehow acts to mitigate their actions is a real puzzler.
Name one instant, one time, one snippet where Canada criticized or second guesses their boss's actions or wishes, anywhere on the globe. Canada happily lets them torture a citizen for years, while all the toady opposition sits on their hands and wonders whether it'd be better to torture him here instead.
Canada's presence in Afghanistan does serve a purpose to the Americans: it gives them international cover, allowing them to maintain the fiction that this is a NATO operation. The Canadians also act like the low-rent colonial troops we've always been to greater power, gladly offering up our own citizens to further the empire's interests.
That is correct, the Taliban would never injure or kill anyone that opposes them, they have never killed police officers, government officials, tribal elders, political opponents, teachers, aid workers in the past.
I'm sure those same victims feel much better, much freer when they are murdered by your side instead.