It's a good question, and I'll be interested to see what our political experts have to say. OTL's Curragh Crisis was precipitated by the UK govt ordering British army units to secure arms depots in the Ulster region. Because many of the officers were Ulster-born or very sympathetic to the Northerners,* and felt the govt was behaving in a thoroughly immoral fashion, and they were wary that they might have to fight their own friends and people, there was a strike.
Assuming this occurs before the PoD (i.e. a simple have FF not get shot PoD), then the govt will be very wary in selecting the soldiers it uses for its next attempt. If the Curragh Crisis is butterflied away by the PoD being earlier, and the govt still tries to force things through, then one will have a break-down in govt-military cooperation at a dangerous level at a time when it needs to be at its best.
An interesting point is that IOTL a large chunk of the Ulster Volunteers, on being pacified that Home Rule was to be delayed, enlisted for WWI. In the South, there was a sense of betrayal at the delay, and it was mainly just moderates who enlisted. This had the effect of radicalising the independence movements in the South. So no war, and there will be more reasonable people in the South, and also a load more champing-at-the-bit UVF (or is it UVA? I forget) glaring at them from Ulster.
* The govt wasn't totally stupid. It had a quiet policy of allowing any officers with such sympathies to disappear for the duration of the problem, provided they were actually domiciled in the North. But they forgot about chaps like Gough. For although Ulster-born, he no longer lived there.