It does seem to me like the anti-risk effect from intelligence enhancement would somewhat outweigh the pro-risk effect, but I'm not sure.

It is a hard subject to argue about. If I wanted to criticize you, I could say that higher IQs make uploads less economically attractive as they will start off with a smaller advantage, and higher IQs likely would make uploads intrinsically more difficult. And if I wanted to criticize my criticism, I could say that by making people in general smarter, we increase the cost of labor, which makes mechanical substitution ever more attractive (and mechanical substitution for reasonably complicated tasks implies development of AI/uploads).