If there’s evidence that he used it I wouldn’t be shocked, but the credible evidence indicates he preferred his drugs refined. He doesn’t seem to have grown a poison garden, which is what I’d expect from someone with complete pharmaceutical access that is just into using natural poisons like datura on victims. He’s far more likely to give a modern date rape drug mixed with alcohol, cocaine, or even food or water based on what we know, and for the datura to simply be a beautiful flower that he did brag about its effects, but didn’t use.