I get what you're trying to say, but you're wrong on this. The residential schools was of a piece with other deliberate policies designed to subjugate and destroy the indigenous population like the reserve system, Indian agents, the pass system and deliberate starvation (all of which were crafted by the same architects).
Yes, otherwise known as colonialism. But the residential schools were established after the lands were divvied up to white people as private property. Indigenous peoples were already subjugated. South of us, in places like Minnesota, they were seen as wild hunter-gatherers who were incompatible with white culture and they were being exterminated, even with bounties on their scalps. I think the cultural genocide was seen as a more palatable alternative to the real genocide going on, and that it was felt to be necessary because the previous economy that sustained their culture had already been eliminated.
Perhaps the residential schools actually saved them from total annihilation, giving them a chance to save what's left of their culture so it can grow in 21st century "decolonial" colonialism.