The ROI might not have the means to return migrants so i think the EU will get involved...
Should Sunak allow these people to walk all over the CTA and, in effect, do what Russia did to Finland by deliberately using migration as a weapon, then who knows where it will end?
Sunak is trying to blackmail the EU into accepting returns from the UK, i don't see that happening somehow & you can bet your last euro that he will challenge Labour on this.