The issue with the Giro is that he won't know whether he'll be fresh enough to ride it until after the Tour and then it'll be too late.
The team want to maintain their spot among the best in the world, and for that they need to win big races. The Tour is difficult at the moment and monuments have been tricky for longer, but the Vuelta and Giro have proved to be possible, so I could see the team considering it. Winning all 3 GTs in his career would be a major accomplishment for Vingegaard. Achieving it before Pogačar would possibly be the cherry on top.
They probably won't make the decision for next season until the routes have been announced, although studying them in detail doesn't seem to be one of his favourite pastime activities.