It obviously has to do with freedom and agency. Kuzan wants to get his goal. Dragon may lead there, but that's a long path, given that the RA wants to plan over decades and only strike when the moment is right. It's also more of a passive pathway, waiting for the WG to make a wrong move, empower common citizens to fight for their freedom, lead countries to a rebellion.
Kuzan is more of a direct guy. Like his mentor, Garp, he talks with his fists. BB's path allows him that.
-----------------
But I also believe it has to do with two important OP concepts: inherited will and lineage.
A pattern can be discerned.
Ace is Roger's biological son.
But it's Luffy who inherited his will.
Luffy is Dragon's biological son.
But it's Sabo who inherited his will.
Similarly, I believe that:
Dragon is Rocks' biological son.
But it's BB who inherited his will.
Both Dragon and BB want the same thing, but the reason why they want it and what they'd do to get is where Kuzan's own ideology lays.