Status quo is an interesting concept. The Delta issue came down to hard evidence by a few union officials pushing the "No OT" campaign coupled with a measurable decrease in voluntary overtime flying when compared year-over-year.

Absent the union intervention and "fingerprints," I think a Court would be hard-pressed to issue a TRO to compell pilots to fly voluntary overtime. TROs usually "stop" stuff rather than compell someone to do something....hence the "R" (Restraining) in TRO. Even with past practice (i.e., X amount of trips are covered by voluntary OT), are you obligated to fly over and beyond the terms of your contract? It becomes an interesting legal exercise.

Good luck!