Jack Spirelli describes the Coven of Light as a cult-like organization, with dangerously powerful members and no love for mundane humanity. He was also on record as categorically refusing to involve himself in a case that took him anywhere near the Coven.
Why then had Jack agreed to take the case of a defecting Coven member? His dragon side-kick Marin may not speak to him again–ever. But sometimes the right thing to do wasn’t convenient, comfortable, or safe. It’s also possible the stash of magical potions the fleeing witch had used as partial payment might have played some part in his decision.