Old post, but very interesting to me. All good points about the accordion being able to contribute a lot to any music. I’ve played piano with a lot of great bluegrass players, and I think the key to doing that with accordion is the same: know the tunes, know the tradition, study how the other instruments interact, study the great players and begin by imitation and cooperation. Don’t play so much. Play single notes very often as counterpoint. Play staccato a lot. The problem is not with the instrument. The problem is with the player.
I think that the original post brings up the dark side of the genre. For some reason, some bluegrass players and fans are very rigid in their approach. They simply won’t accept different instruments other than fiddle, guitar, mandolin, banjo, and bass. We call them “Bluegrass Nazis.” Yeah, I’m talking to you.
They seem to be unaware of Sally Ann Forster, who played accordion with the Father of Bluegrass, Bill Monroe, as Jeff of NASHVILLE pointed out.
Bluegrass started as a fusion of many musics, including African American jazz, so the idea that it’s a pure music is probably based on a warped conservatism.