Rogr may not have the leadership feat, but as regent of a domain he can still employ minions. He'd be more likely get someone loyal personally (rather than simply loyal to the crown/paycheck) with the leadership feat but the lack isn't crippling for him.

If changing the scion mechanics from a ability score/feat system to a full class system I'd add leadership as a freebie fairly early on. Whether this is do-able under 4e depends heavily on the new magic system - making a class to beef up either a fighter or spellcaster is very difficult under 3.5e.