That's pretty much what he said about Kings. He can write as aggressively as he wants. But if Scott gets left out of most of background vocals like he did on Kings those riffs will be slightly wasted.
The traditional background yells / screams were more absent on FAK but the melodies / hooks from Joey sounded too catchy for that anyways, IMHO. In a previous interview, Charlie mentioned that during the writing process "the whole dynamic changes after Joey does this own thing and that's the beauty of music"
So starting off with Charlie's aggressive riffs doesn't necessarily mean the new album will be super heavy after everyone else adds their parts/arrangements/compromise/etc.