Before the facilitator asks the participants to be vulnerable, the facilitator needs to be vulnerable themselves. They share a story from their own life in which they committed a micro-aggression. This shows that anyone can be a Initiator, including the facilitator. They share how they responded in a defensive manner, and how they now found alternative ways of responding. That is what works for them, and today is about finding out what will work better for the participants.
The facilitator is leading by example and invites the participants to be vulnerable too.