Sounds like a plan then! Capell is much too helpful for Sephiroth to be doing/saying anything that's going to damage that.

How feral do you reckon Capell is going to be by the time they encounter Jason? Sephiroth will be happy for Capell to lead in until he sees an opening. If anything else he could be a sometime battering ram if his neck pain is too great to fight with his sword by that point.