The only way rape would make his asshole so loose he needs homemade ass tampons would be if either he was raped that same day or if he was raped with a fire hydrant.
Your sphincter is a muscle that doesn't just stop working because something passed through your ass. Otherwise everyone would need ass tampons forever after the first time they took a big shit.
He needs ass tampons because he has a terrible diet filled with ingredients that cause anal leakage and he doesn't know how to properly wipe his ass. I bet he defaulted to "it's from rape" because civilized people would respond with "oh, I better not ask anymore about this or get mad at him about this gross habit".