Im sorry but, Im a lawyer, WhyEm has no authority to tell you that you can or cannot share something that he has no rights to. His pack contains plenty of stuff made by Rockstar, in fact; after further inspection, every single model in "his" pack was made by Rockstar, he just did some editing and is now claiming rights to stolen property. Thats like stealing someones car, painting it and saying it's yours now. That's not how that works. Did he ask Rockstar if he can edit or share these files? I dont think so.
RDR 2 is not like Skyrim where modding is "allowed" by the creator company. Every single mod made for this game can be taken down by Rockstar at any time they wish. WhyEm is the same as any other modder here(except script mods) and "his" files or rather, Rockstars files, are not free game but are shared until someone gets a cease and desist or a lawsuit from Rockstar only.
The fact that you edited (compressed) those files is the same as what he did to Rockstars files, in fact; what he did is much much worse. He basically stole from Rockstar, made some edits and is presenting those files as if he created them from 0 and distributing them under false pretenses as if they were made by himself. WhyEM is just a power tripper and you definitely shouldnt listen to someone like that. There are no permissions to be given by someone who doesnt have any rights to those files since they were obtained in bad faith.