If they're not building reactors on the land allocated to native tribes, why should they?
That's the thing, they will be on unceded land. As I understand it Canadian settlers signed treaties which allowed indigenous people to retain rights to the land. Canada then violated those treaties and built on land they didn't own. Today Canada is trying to respect the original treaties while also appreciating that they can't undo what's already been done.
First Nations have treaties with Canada with constitutionally protected land use rights that have implications beyond tiny reserves. Rights to hunt and fish can be implicated by heavy industrial land use which compels a duty to consult. Doesn't mean that First Nations can veto a project, but also doesn't mean that all this can be ignored.
All of this is more complex in British Columbia where in many places treaties were never signed and so the land is unceded and under unresolved land claim.