Cora was saying he would have Dalbec workout at SS. The assumption is it positions him to play there if needed.
Like I said before, Dalbec is already on the 40 man. They could add Goodrum once Story hits the 60 day, but that limits the ability to use that spot for anyone else. The Sox have other needs they probably worry about as much or more than backup SS, such as starting catcher, and replacing any pitchers who get injured in ST. And Cora has been reportedly using Dalbec in other positions for a while, including not only SS but also 2b and OF. In fact, there was some needless panic on this board when a story discussed that last season.
Whether we like their defensive abilities and limitations or not, both Dalbec and Duran still hold 40 man roster spots and have been bypassed for DFA multiple times. This does keep both in the picture for reserve roles either to start the season or as injuries occur. At least for now…