after 2 years, if he has seen the negative effects of methamphetamine on his life then he's probably over it. Psychedelics are special but can also give a speed head some of that same rush/euphoria/stimulation so that may be a little triggering for him. If he's dead set on never using meth again he's probably just like anyone else.
If there's still a fantasy of one last binge, then he's probably going through hell trying to fight off cravings while using psychedelics recreationally. Though they may also help in realizing that meth addiction is not a great idea, it could go either way. Stims are a bastard to quit, the cravings are very intense and long lasting but after 2 years, they should be gone. Just make sure that you never bring stims around him, there'd be no way in hell i could stop myself if they were around me, doesn't matter what kind of stim, it'd be all gone and i'd be craving more. Other than that, you should just ask him.