Because the Twins are so bereft of C options one can squint enough to put forth the opinion he's currently the best choice. He's certainly no worse than 2nd best.
They aren't going to go with 1 C on the team, and losing 1 C to the IL (who himself is one of the worst hitters in MLB) put them here. Not losing 3 Catchers. Not 2. One.
More fine GM'ing evidenced.
Now the DH nonsense, you can place that on the huge pile of crap at Rocco's doorstep. He (or his equivalent) has to be rostered. He doesn't have to be written into the lineup when not actually catching.