@Hacete
Can easily be reasoned away with him being held back for one misunderstanding or another. Though I doubt it has anyother reason than it being a grouping the mangaka can use DelinquentXOppaiGlasses
@Katharistis Maybe he is part of Jotaro's bloodline. Jotaro's age was like 16-17 iirc, and he was HUGE! So this dude may in fact be part that family bloodline