According to Osho, he is unequivocally against drugs: they induce unconsciousness and numb misery, whereas meditation awakens consciousness and flowers bliss. Drugs and meditation are opposites; using drugs sabotages inner growth by drowning even bliss in oblivion. Since his entire path is meditation, he cannot endorse drugs; to do so would be a contradiction.
Drugs make you sleepy inside, meditation makes you awake—so if you want real happiness, don’t use drugs.