The North's dirty war involved agents and double agents, collusion and infiltrations. The States either side of the border were involved in acts of commission and omission that cost the lives of the innocent and not so innocent. We had shoot-to-kill, The Commission, Scappaticci et al, etc etc.
So, the authorities have never been above looking the other way when terrorists were being killed unlawfully if the 'greater good' could be served. The former IRA operatives on the ground across the North will know or can discover the identities of the dissidents. I doubt the new boys are being particularly James Bond about it all. However, even if they gave that info to the PSNI, which is sadly doubtful, there wouldn't be enough info to prosecute.
So, should the State look other way and allow the IRA to deal with the dissidents? The dissidents have threatened McG and Adams. So would the IRA have the appetite for it?