Most common medical history items fall under something called CACI: Conditions AMEs Can Issue. (Yes, that's an acronym in an acronym. Welcome to the FAA. AME is the doctor you see for your flight physical, which you probably already know, but other readers might not.) The vast majority of folks walk out of their flight physicals with a medical certificate thanks to CACI.
ADHD does not fall under CACI, and will trigger a deferral to the FAA. The FAA will then refer the applicant to a HIMS AME. (Human Intervention Motivation Study.) HIMS is really about substance abuse, not ADHD, but it's doing double-duty now for things like ADHD and the four conditionally approvable SSRIs. ADHD can also trigger expensive neurocognitive tests ("CogScreen"). So ADHD really is in a separate class of conditions when it comes to getting a medical certificate.
Current use of stimulants is a denial no matter what.
As a flight instructor I think this is completely bonkers. The nature of ADHD is such that if it keeps a person from being able to fly safely, that will show up during training as a failure to meet performance standards. It's completely different from something like a heart condition, where a pilot will fly just fine until suddenly their heart stops. I've taught lots of folks with ADHD diagnoses; almost all of them did great, and the few that didn't were very obviously not able to handle the airplane.