This makes sense. There is no reason to have him on the roster right now. It clears cap space. It allows the Pats to look all off season at what they have. Finally if it comes to pass that the Pats get some injuries at CB then resigning Springs to a vet minimum deal in August makes a lot of sense.
Don't forget that Springs is a good match up in red zone D against big WRs....and there are A LOT of big WRs in the division this year. 35 year old, 13 year vets don't need to participate in EVERY single OTA and practice. I think in certain situations Springs can be a productive player with the Pats, and if he ultimately ISN'T resigned, then it will tell me that BB is happy with his younger, though smaller guys.