As the forward in the AHL with the lowest cap hit, he is probably one injury away from being the first guy recalled.
So what you are saying, is that IF the Canes hadn't signed him, then some other player would be the first call-up. But now, since they signed him, Brind'Amour will be the first call up? So essentially the Canes signed a better player (Brind'Amour) than the one that would have been the first call-up prior to this signing? Ok.
Seriously, if he gets called up due to injuries to a center and plays a handful of minutes on the 4th line, it's still not going to have material impact on the team.
If he gets called up due to an injury to a key player in the top 6, then the Canes are screwed no matter who they call up, as they are already thin in the top 6 and none of their prospects/AHLrs are likely to fill that void. This signing has no impact on that.
Also, Sam Gagner led the Canes in preseason scoring, yet they choose not to sign him.
Pre-season scoring is a meaningless stat and nobody should use that as justification for signing a fringe player. Secondly, maybe because Gagner likely doesn't want to play in the AHL. Lastly, even if he did, maybe the Canes want to use the remaining space in the AHL for player development vs. filling it with a vet. It's not like teams are beating down the doors to sign Gagne.
This signing is much ado about nothing.