@The_Authority
If you debate with Akira Toriyama about Dragon Ball, you wil loose (see what I did there). It's not about what you think you know, it's about what he intended. He excluded battle powers and everything for a reason, that reason was to increase the drama and tension in the fights. Everything that happened was to heighten the suspense. At the end of the day, it all depends on what he had in mind. So you might THINK that everyone knows more about Dragonball than he does, but in reality, the only thing for sure is what he wanted to do with the series. And if he wants to say Piccolo is the strongest you'd have a very tough time proving otherwise because technically, we never get the answer. He could always say that someone was holding back or had a motivation for not going full out or whatever.
So if you debate against him, he'd laugh a lot and tell you what's what.
Don't get me wrong, I'm not saying everything he does is perfect, but what I am saying is that Dragonball is not the real world with real world rules and consequences. It's the figment of Akira Toriyama's imagination; you cannot dictate what the truth is in that world.
Conclusively, if Toriyama has Vegeta stating Goku is the strongest in the Boo Saga, than it's just that.
It's simple really.