He was having a grand time and definitely moving that back toe quite a bit. I would keep working all of his toes to help him get the idea and maybe loosen them up and get him used to using them if possible. The house finch we raised got her foot broken by Nerd bird before we realized they weren't safe together and I used to stretch out the damaged toes and she could curl them back up but the tendons tightened up and she just left them in a ball but still got around fine and climbed and walked. His toes are out all the way so maybe working them will help them loosen up and get him moving them again.
YThey would wrap my broken elbow in nice warm damp towels to loosen up the tendons and muscles before my therapy sessions and it felt great and helped everything move easier. I went from about 30 percent range of motion loss to 3 percent when we were done and I hardly notice it. Might be helpful for him if he'll tolerate it as long as it's not too hot and burns him.