It is still an interesting read though; and I think they both come off well (less so the "obnoxious young men" :)).
Who is right though? It's a morally difficult question because this is not like, say, a big film producer or an indie game developer (representing the two main extremes). This is a girl who (supposedly) wants sheet music for her school production. On the other hand Jason arranges music exactly for those sorts of scenarios; and at what point do you say "this person is now deserving of having the music for free".
Thinking this through there is a fairly easy solution; Jason should offer his music through schools and other youth organisations for free (or free loan). Thus allowing teenagers such as this to put on their shows and practice their art. Then there will be no need for such people to trade the music.
Solution, no?