If you read the study, the kidney injury is secondary to the steroid-induced liver injury so it’s possible this guy could be telling the truth with regards to dosages .. if he drinks and takes Tylenol already, even a short course of oral steroids can be enough to cause the liver injury described here—and the acute kidney injury follows. This isn’t necessarily the result of chronic usage.
His kidney function recovers sufficiently within two months to stop dialysis and that’s also when follow-ups stop so there’s no information as to further recovery but given his younger age and lack of comorbidities, complete or near-complete recovery of his renal function seems probable.