Yes, she could 'take the lane' - but the whole point of filtering is that you don't get stuck in traffic. I'm sure that if you rode this route everyday to work that you'd start filtering here when there was a red light.
Common sense says that cabs are always a risk (in the same way you don't trust dogs off the leash and small children playing with balls), but you wouldn't reasonably expect a car to throw open a door when stopped at a traffic light.
It is stopped in traffic at the red light that is about 25m ahead of it and the passengers have probably though "ah, screw it - we'll walk from here" and jumped out.
I say 'bravo' to her for being calm and for knowing what to do. What would you say about her if she started screaming abuse and obscenities?