All your arguments are weak, besides that Rocks' crew was a crew where the strongest reigned, in this case XEBEC himself was the strongest, that's why they followed him... EVERYONE HAD THEIR OWN INTERESTS, but the strongest reigned.
Cope.
They didn't follow Rocks, and they make it clear many times. He wasn't strong enough to follow, he was at max relative to Shiki, Whitebeard etc etc at the time, and they were still treated him like a clown. Rocks didn't "reign" lmfao, their interests aligned, Whitebeard makes this clear that he wasn't getting ordered around by Rocks. This is simply because Rocks was = to most of his crew and that included Whitebeard, Shiki, Big Mom, etc etc. Rocks was at max equal or inferior to them, and afaik Whitebeard wasn't prime at that time either.
Therefore, its confirmed with this, that no. Rocks wasn't the strongest of the old gen. A argument can be made for the weakest due to his various fraudulent reveals that equally clashing with Harald etc etc. But whatever the case is, he is capped at PK level and no where above.