This is something that I mentioned a few months ago. I don't think it's at all healthy for a two-year-old kid to be taught these songs in nursery.
My nephew can't even pronounce the words or understand what they mean, but he's doing his best to sing them. If this were a song from a Disney movie, it wouldn't really matter, because the words wouldn't mean much anyway and they wouldn't be drilled into him. But he'll probably sing this song in primary many times in the course of a year--for the next ten years. Eventually he'll come to a point when he can pronounce the words properly. And he'll come to an understanding of what those words mean. But by then he'll have recited them through so many repetitions that he'll trust them implicitly. Seven years after that, when he's sitting in a General Conference meeting and the Prophet says that every young man should serve a mission, he'll do it. Not because he wants to or thinks he should but because he's been conditioned to follow the prophet.
My sister is a pretty smart lady. Her husband is bordering on genius. Chances are this kid may grow up to be pretty intelligent--but his ability to think and reason will be horribly stunted by the brainwashing of his parents' chosen religion. That's exactly what happened to me, and it's not right.
My sister thinks that her son attempting to sing "Follow the Prophet" is cute. I think it's disgusting. Something so important as a belief system that may determine one's eternal fate should be chosen by the individual, not foisted upon him from his infancy.
It may be a very uncomfortable experience watching this poor kid grow up.