Even if you had BasicMed, there are a list of medications and conditions that, once discovered, will disqualify you from flying for good, no questions asked, no wiggle room. Sounds like in this case the former buyer is taking meds on the "DO NOT FLY" list.
Hope she sells quick, Dale, and the buyer is either someone in the club, or becomes a new member.
I just read a short list of what FAA calls disqualifying meds.
https://www.faa.gov/faq/does-faa-ha...-pilots-can-and-cannot-take-while-flyingMost of them have pretty short half lives in the human body and should be safe after the effect wears off. A few of them don't simply wear off, and would have to be tapered with chronic use. Their list of tranquilizers, opiates and anti-psychotics are not easy to just stop and say you're OK. Their list of tranquilizers: chronic use can lead to withdrawal seizures if you miss a few doses after chronic use; opiates build a tolerance, are addictiive, and make people agitated during withdrawal; antipsychotics, with chronic use, lead can to movement disorders. So I can see why I woudn't want to fly if taking those.
Of course, there is one over-the-counter "medicine" that has potentially worse long-term effects than all the rest: Alcohol dependence can cause withdrawal seizures, agitation, movement disorders, even dementia,
The other medicines on their list I linked should be safe enough after the effects wear off. I'd wait at least a couple of days to be sure. I don't know what the FAA says about that, and I'm NOT giving advice--this is just a comment. It's FREE. It's worth what you paid!

If I had a ton of money and my retirement well covered, I'd buy his plane and have it tastefully gone through, fixing any squawks without changing its character. Then I'd donate it to the Cessna 150/152 club foundation. It could be flown by a different member to the fly-in every year in Dale's honor. Of course, Dale could fly it himself as long as he would want to. I don't have my retirement well covered and I don't have a ton of money. Darn it!