Looks like in this setup, people only join their office room when they're open to being interrupted:
"When you are online and able to be disturbed, you join your office, alone."
"When you are online and able to be disturbed, you join your office, alone."
In the office scenario, I as the interruptor take on the burden of finding out when someone is open to being interrupted (and it's not that hard). For example I can just say "I'll ask him the next time I see him" and wait until I see him go to the coffee machine or the bathroom. Or, if it's more urgent, I can take a peek in his office and see if he seems to be engrossed in thought or more relaxed.