Chesty
Can't for sure, neither can you. Crews arent shuttled around for a lack of something to do. They were on the plane to fly something at the other end or position themselves for a later flight. SDF isn't a crew base for the contracting airline, so they weren't simply going home.
As to why a charter isn't set up, you'd have to ask the upper echelons of management, which I'm not. I'm concerned if the front line folks did their job, not why management doesn't have Lears plying the skies with DH'ing crew members.