>>282010931
He wasn't being sincere about having fun with Denji, because he was constantly trying to erase him, first via Asa and then via sex with Fumiko. Your biggest clue to his dishonesty was when he told Denji about "his role" on being Denji body guard, only for us to find out in the end his "real role", the one he's thankful for, is him being the switch to Denji's execution.
That's the literal polar opposite role of everything he was talking about during the chapter. Bodyguard and executioner's switch are two opposite roles.
