Why Sinn Fein in government in Republic would hinder and not help cause of a united Ireland

The southern general election, in which Sinn Fein became the lead party, is profoundly disturbing and will seriously impact upon politics here. The vote for Sinn Fein in the Republic was essentially a massive protest vote, particularly by younger voters, not just against the outgoing Fine Gael-dominated government of Leo Varadkar that had been in power essentially since 2011, but also Fianna Fail, hitherto the main Opposition party.