And esp. "Here's to the Ladies Who Lunch," the last verse, when in this production Patti Lupone turns to Rosalie Craig and sings, "Here's the ladies who watch/Aren't they the best?/ When they get depressed it's a bottle of scotch/ Plus a little jest." And THAT's exactly who Bobbie has been throughout the evening.
That's an interesting point. (I haven't seen the production, so I wouldn't have realized how that would have been staged.) Of course, there are other moments in the original show that point to Bobby as more as an observer than anything else - but you're right that this would bring a further dimension to the character.