Manga and anime are done by different people with the same general plot but that's it. How they get there is up them. So there's no such thing as cannon with this one. Toriyama isn't doing the manga so can you even count that as cannon? In the manga Vegeta can turn into SSR and uses that against Goku Black while transforming into Blue right before hitting. That alone is very different from what we've seen.

I'm sure the manga will explain the selection process differently. Because honestly this sucks. Yeah master Roshi knows tricks let him on the team. Raditz alone would kick his ass.