I don't think the Republic of Ireland has a good alternative.Given that the rest of the EU has been giving RoI a de facto veto on any UK withdrawal agreement, and given that the backstop appears to be the only complete deal-breaker here, they could have compromised in various ways that would be strictly better for them than driving everyone into a no-deal outcome.
For example, accepting a time-limited version of the backstop while May was still in charge would probably have got the WA through the UK Parliament. Brexit would have happened, defusing a lot of the political tension in the UK and liberating the EU27 from having a half-in, half-out member and all the attendant uncertainty. Everyone would have benefitted from a more orderly transition, including keeping the Irish border open without needing checks due to either WTO MFN rules or the EU's need to protect its overall border. There would have been perhaps another 5-10 years to clarify the future relationship and resolve any issues still arising at the Irish border, which would have been a far more plausible than magicking something up overnight in the event of a no-deal outcome. And the EU would have been dealing with a basically pro-EU government in the UK while that was going on, at least for the next few years.
That possibility appears to have been lost with the arrival of Boris Johnson as PM. If the Irish do want a 23:59 reprieve, it's going to cost them a lot of political capital to get it at this point. But realistically, I don't see that happening. I think they've blown it, and either a no-deal Brexit or a UK general election that certainly could result in a majority hard-Brexit government now seem like the most likely outcomes.
Critics often say, with considerable justification, that this is a mess of the UK's making. Certainly the UK's negotiators haven't done very well in all of this. Still, if we're playing the blame game, I think there is plenty to go around. The EU's rigid approach and negotiating strategy also caused problems right from the start, and the Irish hardline stance on the backstop in recent times has essentially sealed their own fate. It's all very sad, because it won't matter whose fault it was if a decade from now, as the Irish government's own commissioned analysis suggests, their economy is still significantly smaller and real terms wages are still significantly lower.
I still don't understand why both sides went into this with such an adversarial and rigid approach to the negotiations. There was so much common ground that could have been established early on, and if we were going to have Brexit, we could have had an amicable separation where we remained good friends even if by mutual agreement our relationship was not going to be as close as before and we'd each gain a bit more flexibility in other respects. The whole thing just seems like not only a huge missed opportunity, but an opportunity missed by following a process where glaring mistakes were made by both sides and both sides refused to then fix them even when they were widely criticised. It's just... sad.