The Importance of Opening the Door

You don't open the door unless it's very clear that they're coming in behind you. What you could do is get to the door, realize the person's approaching you, but it's ambiguous. Just tie your shoe or something. Buy some time. Find out what they're going to do. Act decisively. If you see anyone's holding, so even if they're super far away, if they're coming towards the door, you make eye contact. I think any awkwardness from that is still preferred to the difficulties of that person having to deal with the door and the list of other people who might not be able to reach it.