Option 3 is more likely to be the case. Bringing in Goins simply adds more depth to the Royals infield. Having a veteran player like Goins could dramatically help. It provides insurance in the case of someone not panning out at their position while allowing the Royals to have a veteran that does not have to play.
When the Royals signed him they signed him to a minor league deal, which is significant. The deal came with a Spring Training invite, so he will have to prove why the Royals should put him on the 25-man roster. If Goins can outperform Torres, then Goins will most likely be a bench player. If Mondesi or Cuthbert struggle significantly then Goins could be an option to fill that hole.
Going into a rebuild, it makes sense to allow players like Mondesi and Cuthbert to fail. The Royals desperately need one of the two to work out an become a long-term solution. The rebuild honestly depends on it. If Goins can prove to be a mentor for the young players, perhaps this minor league pick up could benefit the Royals significantly.