But there are qualified actresses out there who are deaf. Take Marlee Matlin, for example. A highly successful career and it all started because someone gave her a break and she starred in a movie about a deaf woman. This is an opportunity for someone from the community who is representing a pillar of strength in the deaf/blind world, to portray her. That would be a huge honour from an artistic point of view.
That being said, Broadway has been taking a big hit over the past 5 years and even off off broadway shows are having trouble meeting budget so I can see why the director made the decision that he did.