Matt, based on the description in the Wiki there it seems like there might be some bugs involved here somewhere. I left details below. I'm not going to complain any as I don't feel an overwhelming need to keep the feature turned on, but if there's any further information that I could provide you, let me know.
Volume protection does the following:
Makes it so that it isn't possible to increase the volume by more than 5% at a time (so accidentally clicking 100% on the slider will not go to 100%)
For me, the volume seemed to actually decrease rather than avoid increasing. This could just be GUI issue though. I see a "spasming" volume slider when I click and pull.
Makes it so that starting playback if nothing has played for 30 minutes sets the volume to 20% (unless the volume is already lower)
I was definitely seeing the volume change between tracks in a playlist, so the "nothing playing for 30 minutes" bit was not being followed.