May be they tried it already without success. Not sure if Tourist Visa would be applicable as he would be earning money in Germany (don't know the technicalities).Should've applied for tourist visa in December itself. Guess it would be easier to get that. Anyway, the tournament is only for few days. I remember shegen tourist visa was given in a couple of weeks. You just had to show the hotel bookings and return ticket.
In any case, Tourist Visas can depend on your country & whether you have traveled to EU before & other factors apart from just travel itinerary. Not to mention you do not want to do something wrong without knowing it that could be on your record forever & might affect your future visits to EU & other regions.- lot's of complications and paper work, since Germany apparently is really scared of Vietnamese ¯\_(ツ)_/¯