BECAUSE THINKING ABOUT THE PEOPLE TURNING TO DUST PART IS HORRIBLE AND HE'S TRAUMATIZED AND SOMETIMES YOU JUST WANNA THINK ABOUT SOMETHING NORMAL LIKE SCHOOL???

"Yeah, it uh, wasn't a good time. Fun fact for you, though. Sometimes these weird places that kidnap people from other universes can bring people back from the dead. That's a thing I found out." Shrug, after a year and a half it isn't even weird for Peter anymore.