Based on how he listened and responded to interviewers immediately after the race, my gut tells me that he's probably a very good student. Early in the school year quite a bit of material is usually review, or closely tied, to concepts from previous courses. I doubt he will have much trouble getting ahead of the game before he leaves and catching up when he returns.
Furthermore, everything about a trip to the World Championships will be an incredible learning experience that we can only wish most students could have.
I imagine his teachers will cut him some slack in getting caught up just as they would for any student out two weeks with an illness.
I completely agree with going and enjoying the experience with no real pressure - everything's gravy at this point.
If you were to suggest signing a professional contract between now and Worlds, I would not be on board with that.