It's not the age that's import, it's the readiness. Even with the age change, We've had a few boys in our ward wait until 12 or older because they didnt feel ready. My friend's daughters all had to wait to be baptized due to their father. In the end, they were adopted by their step dad and he was able to do it in a very special new-family-starting-over way.

He needs to tell his quorum what's up. And offer to serve in other ways. Maybe he collects the bread from the person donating weekly, or is on door/greeter duty helping to Sacrament passers go to the lobby smoothly. There are plenty of ways to serve while he waits.

Other than official duties, I cant see why he cant attend any activities, YM, camps, etc are all still open to him. (Correct me if I am wrong, I'm a lady)