Haha, cool, good on him then lol. I guess that explains that response!
There are indeed a few solutions that Luke could take, including setting up his bike better, investing in a longer mod frame, or investing in a stock, or a 24".
My first suggestion was to try a stock and make sure he likes it first, which is still the best idea. Seeing as everyone is different, it could well be that he turns out to be one of the tall riders who uses a mod.