I think it is completely fair for a product vendor to not want to be related with an illicit industry. They are simply trying to protect the image of their company among people who actually grow things that are legal under federal law.

They probably don't want retailers to stock products like Advanced Nutrients, because Advanced Nut. is a cannabis specific fertilizer.

They're obviously afraid of getting in trouble and are just trying to cover their asses. I imagine they're just following the directions of their attorney.