1. Either you believe that the Silver Sea is a creation (which means that its an extension of the statement that Venuzdonoa can destroy all of creation, and therefore can destroy the Silver Sea) or you don't believe it (which means that the statement about Venuzdonoa being able to destroy all of creation doesn't apply to the Silver Sea regardless, and as such, there's no proof that it can destroy the Silver Sea).
2. I don't need scans to disprove headcanon. It isn't stated anywhere in the story that the Silver Sea is made up of Fire Dew.
3. Again, I don't need scans to disprove headcanon. We know for a fact that all Worlds in MGnF were created by Gods of Creation. However, never once has the Silver Sea been stated or implied to be a creation. If nothing in the story itself suggests that the Silver Sea is a creation, why do I need to prove it to you? There's nothing to prove to begin with.
4. Venuzdonoa destroying Graham who is "beyond reason and logic" isn't nearly enough to prove that it can destroy the Silver Sea. On top of that, Graham's nothingness existed beyond the nothingness that Venuzdonoa destroyed, so Venuzdonoa didn't even truly destroy Graham. If Venuzdonoa is some omnipotent weapon that can literally do anything, it would've completely destroyed even the nothingness that existed beyond what was destroyed. Furthermore, compared to some of the deeper world characters, Graham is fodder, so comparing him to the entire Silver Sea is utterly ridiculous.
5. None of the points you brought up have any solid grounds. You talk about Venuzdonoa being capable of destroying the entire Silver Sea as if it's a fact, but every point you make is utterly shaky at best. If you don't at least have a strong argument for why Venuzdonoa is capable of destroying the Silver Sea, then it shouldn't be treated as an undeniable fact.