The information on Uniform Transfers to Minors Act is located in PA Commonwealth law 20 PA C.S. 5301-5310. The donor is making an irrevocable gift to the minor and appointing a custodian. It is possible that the donor and the custodian are one in the same person. In reading the regulation it does not appear that the custodian can borrow against the account, unless of course there is a direct benefit to the minor. I would use caution in allowing anything that is not clearly defined. The bank could be liable to the minor when the minor reaches the age of majority and wants to know what happen to his or her money.
My opinion only ... which has not been considered to be valuable by anyone but they keep asking for it.
I stopped worrying because it doesn't make any difference. However it does amaze me some days on the depth of their lack of knowledge and the attitude when they are told something that they don't want to hear. It only proves the point made years ago by an operations/compliance person who said "Everyone's got one and some people are one."