This is exactly why you'd be hard pressed finding an Indian who supports this. Alberta is reactionary as all hell. The capitalists get rich by plundering the land, and Alberta is quite rich in the resources that they're after. But the pesky treaties with us, and government oversight is a foil for making even more money. It's clear that if Alberta separates, they will cease any lip service to the treaties with us.
Also, as pointed out by several others, Alberta would be immediately snatched up by the US. This would be disastrous for everyone but the US.