I think what you're asking about is divine command theory, not nominalism. (Nominalism is a metaphysically antirealist position whereby there is no standard by which "goodness" can be measured; divine command theory is a metaphysically realist position whereby God's arbitrary decrees are the standard by which "goodness" is to be measured.)
I don't know if divine command theory has ever been condemned as heresy, but I do know that most Catholic theologians have rejected it. (Because most Catholic theologians say that God's decrees are not arbitrary to begin with, but that God's decrees follow necessarily from His nature.)
With regard to ceremonial laws though (e.g. circumcision), I think divine command theory is actually true. For these particular laws, there really isn't an answer "why" other than "because God commanded it". Catholics can (in hindsight) explain the fittingness of circumcision by pointing out its deeper significance (anagogic, allegorical, and moral), and I think Jewish commentators have tried doing this too, but the fact remains that God didn't need to command circumcision. And if He didn't, it wouldn't be binding.