Skip the Evil for a moment. Good energy is capable of killing Neutral people.
A Holy Word cast by an 11th level caster will kill 1st level Neutral people. The majority of people will be 1st level. A cleric of a Good deity, or of the "cosmic force of Good", using Holy Word in a crowded city, will kill innocents, and will likely Fall and lose their powers.
Good "taking away the power after it's been used to kill" is really no different from a cop having his gun taken away after he's shot someone innocent .
It's the right thing to do. If the "cosmic force of Good" is incapable of acting before a person abuses the use of its power, only after, no "hypocrisy" is needed.