“Zionism” is such a misused word mainly because of Nazi propaganda in the early 1900’s. Most use it in a way that just repeats their lies. Ireland of course belongs to the Irish in the same sense that Israel belongs to the Israelis. But you don’t hear Leftists say “Throw the Irish out of Ireland” like you hear them say “From the river to the sea”. A slogan which they got from Hamas.
Still and all, being against “Zionism” means that one supports the cause of the “Palestinians” in some way, especially in Ireland. So if you’re pro-“Palestinian” in any way, you can’t truly be against what Varadkar’s doing to Ireland.
PS. I got the man’s name wrong; it’s Niall McConnell.