No.
Did you know the Cubs has had two winning months (June and July) and a .500 month (April) that surrounds a disasterous month(May)? Just 5 more wins in May and the Cubs are RIGHTTHERE with the Reds/Brewers and nobody would even questioned the Cubs buying. The fact that the Cubs players fought tooth and nail to get back to .500 shows that this team has fight in them and Hoyer is doing the right thing by rewarding the players by going to get reinforcements.
If the Cubs were further back than they currently are, I would agree with you, but the Cubs getting back to .500 with that 8 game winning streak and are in striking distance of Brewers/Reds and selling would have been unwise.
Besides, it's not as though Hoyer is trying to go all in. So far he has been pragmatic. Best part of Canderlario is that it is likely the end of Patrick Wisdom in Chicago. With Madrigal, Morel and Canderlario, there is no need for Wisdom. That, in itself, is a win for the Cubs.