As a Roshi fan (that is, the 22nd Tournament Roshi + his heroic stand against King Piccolo), bringing him back for the tournament. . .is a mistake. Yes, he's basically been the best thing about the entire tournament, I know that. But it's basically ignoring what the character decided back in the day, to step aside and let the new generation shine. And suddenly, out of nowhere, he's above Ten Shin Han because "he's been secretly training".
It's ok to like one character more than others and favor him/her. . .but there has to be some consistencies, and I'm not even talking about powerlevels (even though the mere though that Roshi could best Ten Shin Han in a fight after all this time is beyond stupid, but wathever), I'm talking about character motivations. Roshi retired and let the next generation take the reins, as simple as that. And he did it happily and proud of how everyone was growing. So yeah, even if he's been the highlight of the arc, at the same time, his appearance represents everything wrong with Super's writing, that is, basically fan service.
Yeesh that does sound dumb. Especially because it was against Tenshinhan when Roshi finally made that choice to step aside. Really shitting on the character.