Could be true, but it's certainly not "obvious". There are myriad reasons (especially in the USA) why people might not vote that nothing to do with their political opinions (ideology or intensity). I am sure that a significant number of the 120 million non-voters were "not motivated", but not all of them. And of the "not motivated", it is hard to know the real reasons why and what it means. Some of them, for example, would never vote, regardless of who ran or what the platforms were. Maybe some of them would vote for radical progressive if there was one with credible chance of winning. Maybe some of them would vote for a blatantly Mussolini-inspired candidate. Either way, it isn't obvious that motivation was the reason to not vote for all of them and it certainly isn't clear that they are more likely to be "latent conservatives".