No, I don't think you're being unfair. And I think it depends on each child too. With me I think I was a lot more mature than my brothers are when I was their age, and I had a plan i.e. going to uni, etc. And I was in a serious relationship (with DH). So, I think these things made me more mature and I would have spent money on more useful things than they would! They are still at the partying stage whereas I was more mature at their age so I guess it just depends on their personality, what stage their at, and what's going on in their life. If you don't think he's ready then I think you would know best and it's a good decision!

ETA- Oh, I just said the same thing as dachlostar but that wasn't there when I posted, lol.