Piccolo asked to see his speed, the implication here is that he's still working with him to see where he stands. Gotenks said he was fast so he was super strong. This is fallacious. Piccolo had no need to doubt his power, so that argument is rendered invalid. But what else do I expect from Gotenks enthusiasts? As long as it helps your case, any mere implication -no matter how small, is food for you.
And if you want to argue 'statements', two can play at that game. Give me one statement that directly says Gotenks SSj Pre proved to be stronger then Innocent Boo after he merged successfully into a Super Saiyan.