Quote: " For example, only men may qualify for male roles in a movie, and only men or boys of a certain age for the role of a teenager. "
Really bad examples, since men historically played female roles during Shakespeare's time.
So a lawyer could easily argue that either gender could play a role, regardless of what that character's gender was.
Also bad for the age example, as it is common for actors to portray characters younger than their actual age.
Just sayin ...
Did any of those cases involve a woman who was better suited for the role than the man?
I highly doubt it.
But go ahead and cite cases where a woman sued after being denied a role that went to a man.