Aside from blueprinting being broken, this works as intended and I don't want to add an extra limitation on reading just for this reason... Admittedly the the recipe combinator could use a better explanation, maybe I'll finally get around to it one day :|
Non-recipe signals aren't ignored because of performance. Always using the highest value signal allows me to skip the vast majority of the logic as long as the highest signal doesn't change, which I deemed worth the tradeoff.