You have some options. First, you could just thread these adapters onto the presta valve(after opening the presta valve stem cap) and use a schrader-style pump, that's your cheapest option but I've come across a very few schrader pumps that don't work with this. They were unable to pass air to the tube. Tell him to be sure to close the presta valve after filling.

If he carries a backpack or has a free bottle cage mount on his bike, , he can carry a compact pump , they often will work with either valve. Full disclosure that it can take quite a few pumps to get the tire to the proper pressure.