And he says right there that captains also often get bigger increases than the individual members. Remember, the original question asked about subordinates getting bounty increases, so that's specifically what his answer focused on.
Also, lol @ presenting headcanon in premise, then begging the question.
Your OP is full of too many assumptions on the specifics of bounty increases. Half the crew didn't get any boost from Luffy's 1.5B.
Even the captain boosts don't support your agendas. King's bounty is proportionally bigger than Katakuri's in comparison to their respective captains. 1.39B/4.611 is %30 while 1.057/4.388 is %24. Any way you slice it, Kat is inferior.