For those who actually know the play, they may realize that naivete of Anne's character is one of the hallmarks of the piece, and if you have had time to reflect on that age, you are going to be hard pressed to show that trait, acting talent or not.
For those talking community and high school casting....it's not valid, the comparison of the Broadway casting IS valid, and those mentioning far away should know that the theatre at which this is being performed is a 650 seat thrust stage. Most of the audience will be quite close and Remy does not look 13 or 16.
It also depends on the type of show, for this non fiction drama, it would be more appropriate and to cast closer to the age, then in other shows.
"He wants to know who cares. I care you stupid fool we all care..." John Wilkes Booth (Assassins)