TLIK, Why so harsh about Reb Zimri? Gedolei Yisroel (the very same ones you cited) say he too was a choleh. Zimri’s childhood rebbi was much too harsh with him. He gave him underserved petch when all Zimri needed was love. Zimri’s rebbi embarrassed him instead of hugging him. No wonder his difficult childhood resulted in what happened later on. He was a baalei aveiroh at all. Zimri was suffering from a dreaded disease. He was reacting with psychiatric symptoms to events and situations that drove him to rebel.
Yet Halacha l’maaisa today is that we now here in America are deputized to be a Pinchos in our times. Check the local copy of your Shulchan Aruch. The very same S”A that tells us that, today, we are to (physically if necessary) punish wayward Yidden who violate בין אדם למקום.
Now about your rosy picture of Moshiach. Have you read the Seforim HaKedoshim about him? It will be a time of great tribulations. The Seforim tell us that Moshiach, even he comes, will expell the Jews who are undeserving. And that can be many, when a majority. Do you remember that by Yetzias Mizrayim fully 80% of the Yidden, bring undeserving, were caused to perish prior to the Geula?