No we have confirmation that Nocturn was immune. It said so in one of the comics. I don't see why everyone thinks Ehlek didn't get mutated. The Barraki were described to have been handsome rulers and in the prime physical condition. Ehlek was native to ocean, so he has probly dealt with some funky water, but was still mutated a little. His face, base, and musle tone were probly changed. But mainly he is from the ocean, that is probly why people don't think Ehlek was didn't get mutated, to awnser your question.