Goku appears to have gone all out against the Devil though, so there’s no evidence for this on this one either.
Goku appears to be using full power against Devil and Gohan.
Well, that goes back to my initial point, to which you used the Roshi example. And with the Roshi stuff, again, it'd only work if we assume Roshi wasn't going all out in the 21st Budokai, I get it. But IMO that is harder to assume, because Roshi resorted to desperate techniques like the sleeping hypnosis and the Bankokuri Biku Sho (or wtv the name is, it's that paralyzing pulse chi, high frequency ki)... He clearly felt he was on the verge of losing if not for those.
Goku didn't come to the point of showing that same urgency, that "do it or lose" high pressure vs old man Gohan. The fight against old man Gohan was a close one, but it's not like it extended to a point Goku felt like "I may lose this..." or went for whatever means necessary to win. Under no other information, like, if Tao Pai Pai were not questioned to have beef defeated at any moment, of course there would be no basis to assume anything like a match level in the Baba tournament... It'd have 0 basis. If Goku were close to losing (that tail squeeze doesn't count, it's Goku's weakness, which shows old man Gohan was the one on the verge of losing), prompting Goku to use malicious techniques to win, then I think the assumption of a match level would be even less likely... Like the Roshi stuff vs Goku in the 21st Budokai.
Still tho, maybe Roshi was taking into account his special Paralyzing Pulse chi as a valid factor that put him >> that Goku. Even if in hand to hand, no special move factored, they were even, that high frequency paralyzing ki attack had a legit importance in the fight, was part of Roshi's vast skill set, and would make Goku surrender if not for the full moon. Perhaps by seeing Goku's casual one shot KO feat vs someone slightly above 21st Budokai Goku (the Mummy), Roshi realized that not even his best attack that worked before, would stop the Goku from then.