I'm sure he is. It's still offensive, since by no stretch of the imagination did his situation match that level of coercion.
It is not only people in prison or people in abusive relationships that use that word. It is a commonly used word among American youth, It is often used in a comical way (see "I'm Rick James, bitch!), it is often used in an affectionate way between friends, and it is often used in a harmful way.
Your personal tragedy does not give you ownership of the word. It does not give you the right to dictate the way that society uses that word. People will continue to refer to their friends, enemies and victims as their bitch no matter what you or I think of it.