I think you misinterpret. With "they" he meant whomever killed Montagna at the time and then he implies that the ones who did it would be in trouble because they killed a capo of a large family. It is interesting that he refers to Montagna as a capo, but perhaps he meant capo in the general sense.
yes, i think you're right, he meant this... and it confirms the bonanno's have still a big influence over montreal
