To equate giving all of the funds to other charities and not allowing any of it to be used for its given purpose with giving the rest of the money after its intended purpose has been met is... well, not right.

Like, consider a non-profit that you want to support its vision. Most of the money goes to its mission, the rest pays its execs. They decide to use 100% of it for the execs. According to your argument, that's just fine.