I am in accord with prior posters...with less than 24 hours notice on the change, you can't require the designer to be there at the start. If this were a previously posted schedule it would be a different story, but as that is not the case, the SD was justified in his statement.
Balancing your work in theatre and your spirituality is the same as any other balancing act in the life of a theatre professional. This is one of the things I love about catholicism...there are a million different mass times, any church you go to will (basically) be the same, and it's only an hour! (I swear I don't mean that to sound as shallow as it does...) But seriously, it's nice. So even if you have an 8 am load in on sunday, you can go to mass on saturday afternoon or evening or even find a 6:00 am mass sunday morning.