Your friend is right. Not knowing is the worst. But it doesn't have to be that way.
Have they looked into hospice yet? Hospice is usually great about filling in the blanks and making sure patients get all the info they need. They are patient advocates.
We have a friend who was recently diagnosed with Lou Gehrig's disease (ALS). Hospice has been great...they've arranged for equipment, medications, care-giving, you name it. They've also brought him lots of info about what to expect and the best way to manage the dying process on his own terms. It's made him much less fearful.
Encourage your friends to look into hospice as soon as possible. And be aware, there are lots of hospice organizations out there. Some are better than others. (And they're not all non-profits.)