How would this be considered unethical? Not only aren't you breaking any rules, you're not even bending them. Since you are also willing to pay the $100 re-deposit fee, I suspect the airline will have no problem with what you are doing either.

As a side note, when I was booking my honeymoon, I had a couple of different agents working to put the trip together, so that I could compare prices. Unbeknownst to me, they actually put a hold on a room when preparing a quote - so at one point I had four rooms at the Four Seasons Hualalai being held in my name. Needless to say, the FS was not happy, and they let me hear about it.