R.M.
Hi RR-
Pull ups are great for Mom/ Dad, but not for the child. One reason kids learn to use the potty, is their underwear gets a little wet. Pull ups pulls the moisture away from the skin and the kids do not feel the sensation.
Also, pull ups are easy. Why walk all the way to the bathroom, when you can just go in a pull up. For you & I that would be weird, but that's how he's gone to the bathroom all his life, so it's normal for him.
I suggest going pull up free for a while.
R. Magby