It's only an issue if your friend is going to make it an issue. It isn't worth stressing over. Many, if not most, snakes won't feed within a week or two of getting a new home. They like time to adjust, to get to know their new surroundings, and, until it understands that the new people it sees walking around it's new room are not going to eat him, he won't eat either!
To put your friend's mind at rest... weigh the snake each week and record any losses. Too much loss is a problem. Basically, get the temps right, humidity right, ensure that there is a nice tight-fitting hide box and shelter, and wait it out. Don't offer food any more than every 3 or 4 days, otherwise the snake will get used to the idea of having food on demand. Browse this forum, and the morelia forum... there are many ways to get a snake to eat, all listed already. If the settings are right, the snake won't let itself starve to death. It'll eat when it's ready. Remember - the owner is never the boss when it comes to snakes 