Have you read CFR title 38 and what it states about what he went through. It seems he is due temporary 100% sinc he had surgery but I can say for sure.
I have a similar story but is had to so with a hip injury I get while I was in. I had to get a new hip procedure done, which, according to Title 38, is suppose to be rated at 100% for a year then a reevaluation C&P exam has to be done after a year.
What I got was 3 months temporary 100% and they backed it off to 10% since they didn't understand what I got. My report was so funny because they actually copied and pasted a line right out of the procedure brochure to justify their view. I got a new type of proceudure done known as a Birmingham resurfacing but I stil had my acetabular cup ground out on my hip bone as well as the femur getting a new ball put on it. According to TItle 38 any modification to the acetabular cup warrent the 100% TD. Needless to say I put in a notice of disagreement to what they stated. Along with it I pricted out a copy of the regulation as well as a copy of my x-ray of what my hip looks like now. Hopefully they get the message.
Maybe you should do the same. Keep records ofeveryday on how bad he feels and how his movements are. Then give that as evidence. Good Luck.