Harry,

I had over 60% of my tongue removed and reconstructed this past July and I can speak and eat just fine. It took a little adjustment time, but now people can't even believe what I went through. I am even back singing with my church choir and sound just the same. Sometimes my new tongue does get a little tired, and that's when I revert into the language that my husband and I refer to as "Englisp".
I also am involved in a support group at my hospital and know a man who had a complete tongue removal. He speaks and eats well. In fact, he works as a salesman. His speech is altered, but still understandable.
Let your friend know that his first priority should be doing what it takes to keep on living. This surgery may be a little challenging, and it may take some time to get the speech and eating part back, but at least he'll be alive to see another day.