His front wheel is only a couple inches off the ground on with no hill, so his center of gravity on that bike is way to the rear.
If he tries to climb mountains, I don't know whether any amount of leaning forward will keep him from falling over backwards, especially if he means to keep the front wheel from touching the ground.
Also, it's singlespeed bike where you can't stand off the seat because there are no handlebars (although you're near a standing-over-the-pedals position to begin with). Yet another reason I would wonder how he would make it up mountains.
Of course, railroads cross mountains mainly by using roundabout or switchback routes that don't require any steep grades. Is there a rails-to-trails route across the rockies?