Speaking as this sites resident horror fan I can confirm that I was into horror movies at that age. It's possible sure but I'd Desmond hasn't seen a movie scarier than gremlins (still a good horror movie BTW despite the PG rating)
Also
@Thanatos pleas don't compare piggy to Pamela volrhees. At least Mrs voorhees genuinely loved Jason and wanted to do everything she could to protect him. And even set out to avenge him after she failed as a mother. If Desmond dies I'm certain piggy will just think "I Can have another"
Lastly I can't help but think Desmond is going to end up like the Arthur fleck joker. When he learns just how she exploited him for her own personal gain it's gonna be a heavy dose of sleeping pills and pillow over mommy dearests face.