Just call the method if that pleases you. Noone is stopping you from calling an undocumented method. Just don't be surprised that after an upgrade, the method is no longer there, or causes your system to send out spam.

That's what private means. It means the author/maintainer keeps the rights to modify it without notice. I don't see the difference between calling a private method or fiddling with attributes directly. It's great as long as it works. But you've voided your warranty. If you do it with my modules, you don't get support, and you don't get sympathy if your program breaks.