Still none of your business.Once you tell me that you're buying it for somebody else, you're making it my business.
If you won't tell me that this unknown other person is legally qualified to have guns, it is reasonable to assume that he is not.
The only legal requirement if you are not an FFL is to determine that I'm a resident of the same state, and that you have no reasonable reason to believe that I cannot own a gun because I'm a convicted felon.
Of course, if you insist that I tell you that this other person is "legally qualified to have guns" then I guess I will just have to do that, if that's what floats your boat.