And now he will be give the chance to fight for a world title at this division? The only thing that I can think of is that Top Rank wants all money in-house for them and their fighters, so it's easy to make this fight by bypassing Jack.
I think regardless of how we think of that fight, it does make sense for Teofimo Lopez to be chosen as the challenger for that WBO Junior Welterweight Title.
Even having only a few fights at 140 against an "unknown" boxer as you mentioned, Teofimo Lopez is currently the Rank 1 contender in the current WBO rankings in that particular division, therefore, he is eligible for a title match and a challenger.
We can't only blame Top Rank here as WBO itself plays a role in allowing that fight.
Proving anything at the present division is actually not that important these days as the promoter's influence can already get the governing bodies confirmation. Even if he just got a 2-fight with unknown boxers, those are still win and eventually, he will climb the ladder towards the champion and contest their belt.
It's not that new as well because Teo Lopez is not that kind of ordinary boxer as he already made a name in the previous weight class, so, it's obvious that he won't begin at the bottom of the food chain on his climb just like the other boxers do.
Just few examples:
Canelo Alvarez when he fought Kovalev directly
Naoya Inoue will now be fighting Steph Fulton directly