Derech: The source for him being allowed to order other people to transgress is in Rambam Yesodei Hatorah perek 6 or 7, I forget. The nosei keilim bring all the raayos, one of which IIRC is Eliyahu.
Wolf: You weren’t wrong. You should stick to your guns until you’re proven wrong, not just asserted.
Chacham: The chemical difference is not in the chemical composition of the pigment, but of the other organic matter in the substance. The dibromide indigo was not synthesized in a lab, it came from living organisms so there are obviously other factors. I was going to post this on the other thread, but here is just as good.