IRA happy to shoot accused men?

We’ve just heard that the IRA has made a statement saying that it is willing to shoot the people accused of murdering Bert McCartney. It may demonstrate its serousness to the accused men and (perhaps) its bona fides to the outside world. But what will the outside world make of such a threat? Particularly when it’s the general inability to effect due process that is the main concern of both the family and the larger part of outside opinion.