I can believe that. You can't rewrite chemistry to give a helium atom five protons instead of the two it actually has. But you can sure rewrite history. It's easy. Just throw in all sorts of personal slants. When it comes to AP History, I'll bet the conservative objections have merit.
I have heard that some history courses spend almost no time on things like the revolutionary war and the constitutional convention but chapter after chapter on slavery and civil rights and stuff.