have my doubts whether Mozart would write a trombone solo

He certainly knew how to write for trombone -- consider Don Giovanni! He wrote several horn concertos.

The pro-Mozart argument: a student finishing a piece is likely to stay with conservative ideas, things the "master" demonstrably had already done.

Of course, a brass instrument solo in a tuba mirum is not exactly a non-obvious bit of tone painting!

Well, as far as the legal heirs is concerned, I'm afraid I've made up my mind: they are entitled to do as they see fit, alas. If the legacy had been a house, they would be equally free to do with it what they want.

I think that's the only conclusion if you think things through a bit, although that leaves ofcourse everybodies rights intact to comment on it as they see fit, too.

But I don't think you can claim they have some moral obligation to listen to some majority rule all of a sudden, because the legacy falls under cultural heritage, or something.

Which of course brings up the hideous thought that that could entail destruction - don't laugh, since we nearly would not have enjoyed Kafka's works, if his instructions and wishes had been followed. It would all have gone into a fire.

True, Augustus denied his request. Then again, he was a deity, and could do as he pleased. Quod licet Iovi...