OmniSpectra
The protagonist's power is very far from Super Buu's power, Super Buu was an equivalent to Gotenks SSJ3 and Gotenks base. After training in the time room, he was stronger than Goku and Vegeta at their maximum powers.
And Goku, after Majim Boo lost Gotenks' power (when he absorbed him with the fusion) said, "Now even Gohan can defeat you", which indicates that he could also, and it's worth remembering, Goku when he fought with Fat Boo, wasn't going all out (he himself said he wanted Goten and Trunks to defeat Boo, and also said he could have defeated Boo if he really wanted to), another thing that proves this is that Goku fought on equal terms with kid Boo (who humiliated fat boo) for quite a while, so Piccolo didn't even know the true extent of ssj3's power to make these claims.
Aiko7w7:You have to put a little logic into it, in the same manga after training, Trunks mentions that they basically defeated Fat Buu, then when they merge again Piccolo mentions that with that power they can beat Super Buu (although he has only shown one part of its power) from here they already give us to understand that base gotenks is stronger than the gotenks before training, it should be said that it refers to the gotenks ssj before training and this one (before entering the time room) with only the ssj was already superior to goku ssj3 ._., now in the daizenshuu and chōzenshū they explain what I just said