It is not a moral theory. It is an amoral theory.
If I desire to achieve happiness by raping someone, that requires an initiation of force. The fact that it requires an initiation of force does not matter in the least to the fact that it would make me happy.
If that someone's husband restrains me, he is doing so to make himself happy. However, he is also initating force.
Are we both wrong?
The strawman standard of force, or it's converse, consent, will always yield a muddle.
Shalom.
If you intend to continue using it, yes, you may photocopy the definition of "initiating" found there -- but he does want the book itself returned.