The fact that you have to ask this question shows how out of touch you are on the issue of the border.
It also doesn't do anything for your pro leave stance.
There is, of course, the chance you know why the RoI would be motivated to avoid violence and you're just wuming
If it's the latter, it's fairly sensitive ground to be winding people up for the sake of points in an argument.
I'll give you the benefit of the doubt and assume it's a genuine lack of knowledge.
maybe because nearly half the population north of the border are citizens of the RoI.
maybe because a return to violence would mean a serious hit to cross border trade.
maybe because there would be a huge negative effect on tourism Island wide.
maybe because of the threat of violence to the border counties south of the border.
maybe because of the increased cost of policing and military activity.
maybe because of the global damage that would be done to Irelands reputation.
and on and on and on