He's responding to my 3-4 vs 4-3 argument and Carter played effectively switched from a 4-3 to a 3-4 when coming to the Pats.
Well, yes and no.
Carter, who was a very smart player, came over to the Pats from the Skins in 2011 - the year after the Skins new DC, Jim Haslett, had switched them over from a 4-3 to the 3-4, using Carter as an OLB. Carter did well setting the edge, but his sack numbers fell off a cliff (surprise).
Interestingly, this had happened to Carter once before when, in 2005, the Niners switched from the 4-3 to a 3-4 under Bill Davis, who then used Carter as an OLB (and the next year Carter was back in a 4-3 with the Skins).
Anyway, by 2011, the Pats hybrid 4-3/3-4 was completely installed, and Carter and his experience were useful in both alignments and in both roles.
In contrast, Bennett appears to have been almost exclusively a 4-3 edge-player with situational assignments as an interior rusher, but still almost entirely in a 4-3 context. While, in general terms, such a role is used extensively in the Pats scheme, whether or not Bennett would be capable of (quickly) adapting his previous 4-3 experience to incorporate more 2-gap principles within frequent pre-snap shifts, plus much more emphasis on pure edge-setting, is what's unknown. I'm not saying that he can't, just that it's likely more of a question with Bennett than it was with Carter.
Chris Long adapted very well to the change/variety in assignments, although he didn't like it (which is why he pre-emptively declined to re-up with the Pats).