There's scoring quick runs, which any Zak, Ben, or Ollie can do. Then there's consistently making knocks which have outsized impact on match results. The latter is Viv's domain, and I think a lot of people who are on the anti high SR train are missing this distinction when evaluating Viv.
Look at scorecards, match situations, understand that the West Indies lineup, while good was generally relying on him as a lynchpin. And recognize how many match-winning knocks he has, and it's hard to just say "nah he was just a high SR merchant, who got by on vibes".
I don't think he's a great BBB candidate, personally, but he's certainly a higher quality than his average.