I think there's another step missing between being convinced that AI will replace human labor and that AI is the most pressing x-risk (which is the starting point for the article you linked), but this gives me an idea of what the form of your answer would be:

Not only will AI replace human labor, it's also extremely dangerous (for reasons laid out elsewhere on LessWrong / MIRI / various lukeprog-created websites :)), so we really need to solve the more general problem of AI x-risk.