With the final change to John and reality adjusting to his age going forward a number of things fell into place. John's evening of Fortnite was replaced with tossing a ball up and catching it on his bed due to being grounded from screens because he didn't hear his mom calling him for dinner two nights ago... because he was playing Fortnite. A new circle of friends he hopes to one day spend time with came into existence but he knows he forgot a math assignment earlier this week and probably tomorrow, his teacher will send the weekly email to his parents showing he messed up, meaning this weekend and next week will be grounded from friends... The compliment from his mom earlier disappeared, replaced with a simple "thank you, Johnny" as she was just as tired as his father about having to constantly monitor him from doing all the off limit activities which change from week to week.
Simon realized he was the same kind of POS parent they had been and... was glad. The final reality alteration left John in a state of perpetual grounding and any fun he ever had was off limits. Did Simon like himself? Adult Simon was disgusted remembering how severely depressed and hopeless young Simon had been, he wanted to be a better parent seeing the error of his ways with new clarity, but young Simon reveled in the payback. Overjoyed that John gets to feel how ridiculously inhumanely he had treated his son for 12 years.
Mom's turn...
He set things up, just like he had originally planned if perhaps a little faster. Maybe he could empathize with John the tiniest bit having taken on a part of his personality. Maybe he could justify the bad experience for learning but as an adult would no longer feel right allowing it go on. Maybe he was just tired of being unhappy as both a child and adult and wants to just get to the point, he's actually, and only in control of himself.
Regardless, John and Mom would swap places, genders, ages and Simon would let his mom have an afternoon wallowing in the eternal hopelessness of perpetual grounding, then return them and definitely himself to normal. He would leave them remembering that one afternoon as a cursed daydream and he would scrub himself clean of any bit of John's persona.
He would then make himself an underwear model or something and live far, far away from them to figure himself out... Did he hate them? Only a little. He loved them much more than he hated them... but he didn't like them at all. Maybe, after he's gone, they can do better... or maybe they will stay childless and be happier people. After all, not everyone should be a parent.
John became Joann.
Kim became Tim.
And Simon let his young mind slip away till tomorrow evening when he gets to put on the big show for his parents.
Simon programmed everything to set itself up for him, He and his parents will come to the kitchen and sit down, they will be muted and unable to move below the neck. They will return to their normal selves, then Simon will say his peace... he might even let them apologize.