Ethically, yes.
But legally, no.
Jones failed an out-of-competition urine test (December 4), and under the WADA code, cocaine isn't prohibited during the out-of-competition period.
Nick Diaz, Matt Riddle, Pat Healy, all failed post fight tests. So they essentially fought with marijuana in their system.
Had Jones failed a post fight test, he would have been punished just the same as the above three. And the fight would have been ruled a No Contest.
The tricky thing for marijuana users is it stays in you system a lot longer than cocaine.
Ethically though, they are hypocrites. I'd wager they don't give a shit what you do in your own time as long as you don't f*** up their plans. That's why they had no hesitation in throwing guys like Healy and Riddle under the bus.
Hilariously, while marijuana has been decrimilised in some US states, it's still listed as a Schedule I drug, where as Cocaine is a Schedule II drug due to its use as a topical anesthetic, despite multiple studies showing the medicinal benefits of marijuana.