I find it actually quite funny to even considering refusing anybody a trial flight on the grounds they will never get a license. But then again exactly how am I as a Mech Eng degree qualified ATPL/FI qualified to say who would or wouldn't get a medical/license?
Why bother sending them to a doctor when FI's can do it? "2 arms 1.5 legs and you can find the aircraft on the apron your good for me mate" or "sorry pal your no getting a medical cause you have ginger hair it will clash horribly with your High viz jacket and be a danger to other airside users"
Looking back over the years it's definately into double figures the number of TF's I have done that would have zero chance (in my completely untrained opinion) of getting a medical.
H'mm 2-3 Cystic fibrosis kids, 2-3 early muscular dystrophy, old blokes with milk bottom specks or one eye, class 1 diabeties, Coffin dodgers popping angina pills and of course my terminally ill cancer bloke. And they are just the ones I knew about.
Anyway it was done in scotland where the CAA has zero powers of prosecution. I doudt very much the proc fiscal would touch it with a barge pole.
I know what he would take on though a Flying school for refusing to allow a lesson under the Disability Discrimination Act 1995 if there was no safety reason for refusing it. eg I refused one because the lad was epileptic and subject to Grand Mal seizures and having helped with disabled kids since I was 12 in the scouts I wasn't dealing with one of them in a C172. I really wanted to get him up even if it was just in the back but after a discussion with his dad between us we decided it wasn't safe.
So even without reading your posts DFC, I can tell you have excelled again at talking ****e about flying.