Both of these guys are ancient. I wouldn’t care if any of them used drugs (as long as they don’t pose long-term risks for their health) because they might as well be medication. Or are we going to be so dense that the idea that two 80 years olds are likely taking some medication is going to fly over our heads? Furthermore, where do we draw the line of what a “drug-enhancing drug” is? Coffee? Most adults take it to function under inhuman schedules. Adderall? If you do have ADHD, you do also need it to function; if you don’t have it, it’s going be even less useful than coffee. Anything else that they bought at a pharmacy? I don’t care.
All in all, this looks like a talking point made up by people who want to treat politics like a sport, where we’re supposed to watch “athletes” compete with equal opportunity for performance, which is definitely not what a presidential debate should be about.