It's not about the player, it's about the time of year. It's only until the final roster is set, after that you can move a player directly to IR; the reasoning is that they want to prevent teams from using IR to stash players while they have oversized rosters. The problem is that in order to be sure of keeping Gaffney, Carolina would have had to carry him all the way through to the final 53, thus cutting their healthy 53rd choice, setting the roster, moving Gaffney to IR and then hoping that their 53rd choice was still available.
Given Gaffney has a season ending injury it's clear that Carolina aren't trying to stash the player, so this is just New England being the classless cunts they always have been.