Perhaps Fiolar means that many teachers were from Mainland Scotland and did not themselves speak Gaelic, which is certainly true; though it is equally true that many did have that language. The proscription of Gaelic in the wake of the final Jacobite rebellion was a brief over-reaction to an attempted coup d'état, and was repealed once the immediate danger was over. It doesn't have much bearing on policies in Primary education in the nineteenth and twentieth centuries; Gaelic in Scotland represented no threat of any kind, except to monoglot speakers of it whose employment opportunities would be severely retricted if they were unable to communicate effectively in the official, majority language of their country.

While, with hindsight, the heavy-handed and unimaginative methods employed by many teachers in the past are to be deplored, the fact remains that their motive will in the main have been altruistic; I would not subscribe to a conspiracy theory in this case. The situation in Ireland was quite different and not, I think, comparable; though of that I know little.