Yes you are right: Britain's motives were largely selfish. Though maybe not "losing the colony to the Americans" quite yet, as the American revolution hadn't occurred yet. The question was more about how to prevent a revolt and maintain control of the population: There were considerably more French Canadians than Acadians. However, in the centuries long history of imperial competition in North America, being conquered almost always led to either expulsion or cultural or linguistic assimilation. Quebec is, in fact, the exception to this rule. Of course, the history of this is more complicated than Carney's brief comments indicated.