The case for emancipating articles from their authors

In August 1795, the composer Joseph Haydn, on his way back from England, stopped at Passau, where he listened to a performance of one of his most famous works, the Seven Last Words of Christ. He had written this work in 1786, at the request of a Spanish canon, who wanted orchestral music for accompanying meditation during church services. At Passau however, the local Kapellmeister, Joseph Friebert, had added a choir, and made the work into a cantata. Haydn himself had already done a transcription for string quartet, and approved another transcription for piano -- but he had never thought about a cantata.

So, how did Haydn react, after his work was modified without his authorization?