Interesting, and a bit bizarre.
However, I disagree with your formulation "Contributions to a Church to support a child's mission trip are not charitable contributions". The issue in Davis was that the church established the amount but the money was paid directly to the missionaries. I would say that if the church solicits donations for a mission trip and the parent write the check to the church, which now means that the church has control over the money (and could, for example, cancel the trip and use the money for something else, or drop the parent's child for behavior reasons) then it is still a deductible donation to the church. Paying the child's expenses seems to be non-deductible (again, bizarre) but I would argue that donating money to the church would still be deductible.
(It's an arms' length transaction. Similarly, if you give money to a poor family at christmas time, it is not deductible, but if the church board announces "we have identified a needy family, please put your donations into the drop box in the back" then it is deductible because it is a donation to the church rather than a person––as long as the church board decides who the beneficiary will be a not you the donor)
