You are 100% correct here... as bad as Candelario has been, tendering him for 2023 may be the best and most pragmatic move in their view.
My only point for bringing it up is that, based on his overall play, they would be completely justified in non-tendering him. And as much as we think he's still better than Kody Clemens or Brendon Davis or whoever the Tigers have that is remotely close to hitting the big leagues (pretty much only those two guys; Kreidler being injured sucks), I can't say that if you gave either of those guys 250 ABs that they would be significantly worse than Candy has been this year.
I like Candy and he seems like a good dude. And given all the other deficiencies they have on this roster, they badly need him to work out in the short term. But they would be completely justified in walking away at this point.