This. If Max was into his teens, then maybe he'd have realised that from the off. A boy of Max's age is likely more forgiving and won't focus on the reason for the absence or how long it's been, just the now. I wouldn't put it past Callum to claim that Kylie wouldn't allow him to see him, and since he's now there and Kylie's not, it would add up as far as Max is concerned.