- George is an observant fellow
Okay, so change blindness isn't exactly a matter of how observant one is. Our brains just get confused sometimes because they have to fill in a lot of blanks and make assumptions for us to function, and when a change happens without us witnessing it, things can get weird for us.
That said, I feel it appropriate that George just isn't affected by change blindness for some reason, and that Justin is extra susceptible to it for equally unexplained reasons. Granted, I might go easier on Justin in canon, but for this storyline, Justin's got a major perception penalty.