Yeah it's better to think of sober as not under influence / intoxicated, regardless of substance. Like you shouldn't drive under certain medications as it is, meanijg you'd get a DUI, should apply when talking about someone who doesn't drink but does other things. I get the impression he's barely cognizant while even sober, which is probably rarely or if at all, when we see him talking.

Its not or drugs. Its the invisible pen that's up his nose.