You said all of that just to say nothing. The LN is based on the WN. It might change or improve things here and there, but it largely follows the original story in the WN. The LN statement that you keep using is simply a slight alteration of the original WN statement, and in the WN the Silver Sea wasn't even a thing until 10 arcs later, so both statements, whether in the WN or LN, can only be proven to refer to the Militia World. Anything beyond that is speculation.
It's definitely impressive for Graham that he survived Venuzdonoa. However, it's not impressive for Venuzdonoa. Venuzdonoa did destroy Graham's nothingness, but it didn't destroy his true nothingness, which is why Graham was able to come back after Venuzdonoa's attack. You can't keep claiming that because Venuzdonoa was stated to be able to destroy anything no matter how eternal or infinite and it can destroy reason (the Silver Sea wasn't narratively introduced at this point in time), that it can definitively destroy the Silver Sea when it couldn't even destroy Graham's true nothingness. That's just grasping at straws.