A third person in good faith and without court order may act on the instructions of, or otherwise deal with, any person purporting to make a transfer or purporting to act in the capacity of a custodian and, in the absence of knowledge, is not responsible for determining any of the following:

1. (a) The validity of the purported custodian’s designation.
2. (b) The propriety of, or the authority under this part for, any act of the purported custodian.
3. (c) The validity or propriety under this part of any instrument or instructions executed or given either by the person purporting to make a transfer or by the purported custodian.
4. (d) The propriety of the application of any property of the minor delivered to the purported custodian.