What's best for the prospects should be the action that is taken, but also the Twins (and everybody in MLB) want to maximize control. If Culpepper and Jenkins don't have to be put on the 40-man roster, it really doesn't make sense to put them on that roster and also to start the service time clock at this time.
There are only a couple of active roster spots to add on September 1st. On the pitching side, Pablo and SWR are reported to be added and Abel and Bradley could/should also get shots. Any other prospects/suspects probably won't get a shot, even though they have a bunch of disposable arms on the active roster.
I definitely would like to see a healthy Lewis work through his struggles, especially since a lot of his metrics look pretty good. The same for Lee although the same metrics look poor for him. We have had Larnach for four years and he's probably what he is. Wallner has a a poor year, despite a decent OPS, so he's another guy I would like to see the season out. What to do with Clemens? He's slumped miserably, but his overall numbers are far better than expected. Can he be counted on for 2026? Do you give him five more weeks for the front office to make up their mind on him? Buxton and Jeffers should be playing and maybe Jeffers improves his arb contract or is auditioning for a trade. Mickey Gasper doesn't belong on a big league roster from his production this year, but currently he's the #2 catcher. Fitgerald is the only real backup shortstop.