They are using him. Having Jackson on the bench lets them use Jeffers as a pinch hitter on his off days. We have had several lineups with both catchers in them. That doesn’t happen without Jackson on the roster.
Plus Keaschall in the OF.
If the expectation was for Culpepper to immediately contribute in his first 30 plate appearances they should have never promoted him in the first place. Sending players up and down based on small sample size results is stupid and would show a complete lack of ability to assess talent by the front office.
Contract extensions for Lewis and Bradley would be nice. They will need a lefty for the bullpen. They could afford Arraez at second base. The market has several 2B available (Jazz, Gleyber, Lowe).
The trade deadline is in the past. The next opportunity to visit this is in November. The Twins definitely need to trade older and more expensive players to open up spots for younger talent. They should trade Larnach and let Bell sign elsewhere. That is $15M that can be spent on pitching.
Unfortunately Kreidler is so bad on offense that the only positions you can justify playing him are SS and C. The other positions don’t get enough defensive chances to make it worthwhile.