In reply to mysterion:
Having been to Arolla and around that area I was a little surprised that there may be a way to get to Zermatt without touching the glaciers.(In fact we did our crevasse rescue practice in that area about twenty years ago.)
My book(The Haute Route by Peter Cliff 1993) certainly in the walking section mentions moving on glaciers and avoiding the worst of the crevasses.
I will obviously speak to my friend offering the trip about his plans, but catching him at the moment is difficult.