Good point. With the function defined within the module (as is implied), I thought that inheritance would not matter. But if AUTOLOAD gets inherited, then the parent class's AUTOLOAD might want to call the child class's _accessible. I just checked and AUTOLOAD does get inherited in 5.6 (I have vague memories of something about this being considered as a bug and can see inherited AUTOLOAD causing some surprises but can also see uses for it so I wasn't sure what the current state was).
Anyway, I thought that the question implied that inheritance wasn't desired or I would have mentioned it. But thinking on it more, I wouldn't be surprised if that AUTOLOAD was designed to be inherited as part of a technique for inheriting member data.
Thanks for the catch.
(but my friends call me "Tye")