"NOT for human consumption" is a CYA clause so the seller can maintain some level of plausible deniability if the feds ever do try to come down on them. Rest assured, this is lab-grade, high quality stuff. I think they release lab results. DEA: "This fancy new drug looks like another scheduled drug." Seller: "It's not a drug; it's just a compound that we sell as a curiosity so get fucked."

This may hold at least some water in court.

It's akin to the age-old headshop rule of calling bongs "tobacco pipes" and kicking anyone out that calls them bongs.