Detailed Explanation

 Marvin & The Mariner Moose Tip Off implicates the following four laws:

1. An unpaid trustee is liable for losses due to negligence[Choshen Mishpat 291:1].

 2. Appropriate care must be taken that entrusted money be stored in a secure manner by which it will be protected from possible theft and loss [Pischei Teshuva 301: 6]. Thus, a trustee must be wary of the money in his or her pocket before dancing intensely.

3. In a situation where both the owner and the trustee are unsure of the exact amount of the deposit, the trustee need not pay more than the undisputed amount [Pischei Choshen: Halva'ah 2:31].

 4. The regulations of Trustee Responsibilities and Liabilities exists between two parties, not between an individual and a concept.

Just as one may become a paid or unpaid trustee over his or her fellow's property, whereby assuming safeguarding responsibilities and corresponding liabilities thereof, one may also become a paid or unpaid trustee over charity funds earmarked for specific persons. In essence, the trustee assumes responsibilities directly towards the defined receivers. Consequently, in cases of losses due to negligence, the specific receivers may hold the trustee accountable to compensate them for the losses they incurred.

Similarly, an establishment or an organization may appoint a trustee over their funds albeit yet to be earmarked, as the trustee is held accountable to the establishment or organization. Should a loss occur due to the trustee's negligence, the establishment or organization can hold the trustee liable to compensate the establishment or organization for the losses incurred.

However, an individual who holds onto charity funds and distributes them at his or her discretion has not been entrusted by anyone to safeguard the money. In essence, he or she is accountable to no one but an "idea". He or she has become no-one's trustee and is not legally accountable towards any one party. He or she instead has a moral obligation towards the funds. Consequently, while it is more than appropriate to cleanse one's ledger with Heaven and compensate "charity" for the losses due to negligence in his or her trusteeship, the individual is legally absolved from doing so [Choshen Mishpat 301: 5, 6, Nesivos HaMishpat 301: 6, Pishchei Teshuva 301: 5,6,7,8]. 

 Application

Junior Moose

Junior Moose was entrusted by Senior Moose to collect charity funds, safeguard them and deliver the collected money to him at the end of his route. Charity funds notwithstanding, Junior Moose is accountable to Senior Moose.    Junior Moose was negligent in not securing the money before he began dancing fervently.  Consequently, he is legally liable to compensate Senior for the lost funds. As both Senior and Junior are uncertain to the exact amount, Junior is legally responsible to compensate Senior's fund simply for the amount that he is certain that he owes

Senior Moose

The funds  were as of yet not clearly earmarked for specific persons.  Senior Moose distributed the collected funds at his own discretion. Both the city's poor as well as the poor in Israel benefited from his generosity. He was accountable to no higher authority.  As such, while Senior Moose has a moral obligation towards ensuring the collected monies reach their appropriate destination, and should compensate charity for the amount he certainly lost, nevertheless he is not legally required to compensate "charity" for losses due to his negligence. 

Answered by The Fellow - Yesharim Research Center