If he still has his peg, use it for nutrition. He's in for a long haul without taste, saliva, etc. I have been out of treatment for over a year and still no saliva and I am dysphagic, I still use my peg for all liquids. I can eat viscous things with the aid of applesauce.
He has to realize that taste, saliva may not return for quite a while, you adapt anyway you can.
Darrell