Wow, that's very interesting. I haven't seen any use of Bayesian methods along similar lines in music theory -- that is, to try to account for otherwise opaque compositional motivations on the part of an individual composer. I look forward to reading the article more closely, thank you for passing it along.

Where Bayes is beginning to crop up more often is in explicitly computational music theory, such as corpus music research and music cognition. I have a colleague who (among other things) develops key-finding algorithms on a large corpus of tonal music, in which Bayes's theorem is sometimes useful. I don't know for sure how much of that has appeared in print so far, since it isn't my area, but I know it's a tool that researchers are aware of.