[Archaea]

I don't know enough about his training, so I post that much caveat. If I knew more, I could give a better observation.

However, supposing he has sufficient base miles, and really doesn't care about his time, he can finish the marathon in St. George. Mileage is important for two main reasons, with a third looming in the background. First, it helps psychologically to work through distance so that you can do it come race day. Second, it aids in recovery. If muscles and systems have built up strength, you're not taxing them too much to go a little beyond what you've done before. Third, for improvement of time, you need to run the distance.

Thus, if he is willing to throw the time out the window and to know his recovery may be painful, then he should do it.

I can do a four hour marathon almost any time, but if I wish to do a fast marathon I need proper training.