As
@Bigmac said its diffuse thinning and the clinics I said I would personally go to is in my opinion good options. I would say get a consultation with all of them and see what they respond, maybe they are willing to do a small procedure I am not sure.
Please becareful with the cheaper clinics who accept anyone, there can be a big risk something goes wrong and he is left in a worse position.
The thing I say is because if he becomes Norwood 6-7 he might need to shave anyways and when he then shaves his head say if hes 27 years old, he will have scars all over his head, when you are 27 you are still pretty young so you really need to think this through and its not a simple solution with hairloss because of the limitation with the donor area only being able to extract X amount.
Also a potential risk is if he does a hair transplant with alot of minituarized hairs, when he have active hairloss, is that you might end up getting shock loss and lose everything that is minituarized. This is why its often recommended to be on Finasteride for atleast 12 months before coming to any conclusion what to do.
I wish you best of luck, hairloss really sucks.