Money is fungible. If you distrust Alcor that much, why do you expect Alcor to not, say, immediately cut additional funding to the endowment to a minimum or 0; or run up debts expecting to repay them from the endowment once the period expires - etc. etc. etc. This is a classic principal-agent issue and why people want to signal honesty rather than just signing detailed contracts: there are many ways to cheat or violate the spirit of an agreement.