Captain –

Bluegrass came together in the forties and fifties, "contemporary jazz" in this context would have been the jazz of those decades. Jazz was one of the many commercial and folk influences that worked upon bluegrass in those formative decades. Western Swing already had brought the jazz idiom into white country music, Monroe and others merely built upon this.

This really isn't a controversial point. Robert Cantwell, Bill Malone and other writers have noted this influence.

So you don't like bluegrass much. Neither do I, truth be told. But that's not really the point, is it?