I like the idea of "strict protocols," believe me. I just didn't get any.
Anyway, my hip this morning feels ok. Not more sore, not a lot better after the brief ride. But my groin muscle feels a lot better and lifting my operated leg is a lot easier (but still not easy). This was a main reason I got on a stationary bike six months ago - I had a lot of referred pain to my groin and knee. The bike really did the trick. In the beginning, it made it a little worse, but once I started building some strength, my hip felt a thousand percent better. I even considered putting off the surgery. But I knew it wouldn't get any better, so I went for it and am glad I did.
In the end, if you set a seat high enough on a spinner bike and don't reach for the handlebars at all, I think this is lower impact exercise than walking, and involves more muscles. For me, it might be the ideal complement to walking. I certainly wont' stand up in the pedals nor put any resistance on it short term, but I think the working of the groin muscle is a huge relief for me.
Thanks for all the input! This site has been a tremendous resource.