Disputes are best settled in a way that they no longer linger. In the case of Mose Allison, his obituary says he was a jazz and blues pianist, since we never argue with anyone's obituary, that's settled once and for all, "He was a jazz and Blues pianist".
There must be a way to settle disputes of this nature in a non-arbitrary fashion; if "Wikipedia" says it is so, there it is, case closed for this thread.
Music is emotional, and so are we; consequently we must have a non-emotional manner of settling disputes of this nature in this thread, that closes the case. If someone doesn't like the verdict, I suggest they take it up with "Wikipedia".