If a level 1 player managed to get a level 30 shield, let him keep his damn reward. There is no "problem" with a low level character getting a high level item as long as it was difficult to do.
That's not a punishment, its a price of service... if he can't afford it, then he can wait until he can; eventually he can afford to use it more often.
In the quoted example, it is the same reward.
poorly [IMO], but functionally. But there should be another way, that avoids the awful side effects of the method.