Nevertheless, you can understand where Bob and Dave were coming from.
Shane undoubtedly saw the PBS special as the springboard to launch the Trio (his current Trio) back into prominence. Maybe the current group would get that elusive major-label recording contract, radio airplay and TV appearances.
Given that perspective, Dave's comments were guaranteed to set Shane off like a Roman candle.
Dave may have felt used, lured into the project to perform a couple of songs as a gimmick for a show that highlighted and promoted Shane's current group. Dave undoubtedly knew that there would have been no PBS special without the hook of a reunion of the original Trio.