A couple of guys on the 777 have been sent back to JFK after arriving from JFK. They had enough O days to do it. Hoylands answer is "the roster cycle has not finished, so we CAN use you if we want to"
If they tried that with me I would accept the duty then the next morning after I'd had a crap nights rest I would ring and say "sorry not going, not rested"
You don't usually have enough O's after a rostered ULH anyway, but they could get you to do a regional pattern for 2 days I guess.