He said "core-ish barking" so I'm guessing he meant Peter.
I don't want to be one of those "annoying death metal people" who sneer at anyone who doesn't "get" growls, but they predate melodic metalcore and deathcore that you're referring to, and take a lot of talent - just as much as James' clean singing.
Peter is one of the best thing about Static Impulse for me. And I love the fact that JLB and MG went bravely into a new direction, and that JLB confirmed what he has been saying for years - that it's not just his solo outlet and his battleground, so to speak, but a band, his AND Matt's "thing" - by thinking about the songs first, recognizing how cool Matt's voice is and encouraging Matt to put his backing vocals on the record instead of doing them himself, and accepting the idea of having a second singer on board. Not having second thoughts about sharing the spotlight and what have you. And that's one of the reasons why it feels like such a tight band effort.
It's nice that this time James won't be on tour so they'll be able to record everything at once. Kind of hoping for a studio docu.