Independent countries joining defensive pacts is their internal business. Putin wants what he thinks is Russia's god ordained sphere of influence(imperialism), and what's more considers Ukraine as Russia's to rule(imperialism). Everything that was said, and different things were said to different audiences, were just distractions/post-decision excuses. It has nothing to do with defense, and everything to do with imperialism, and generations of indoctrination in it. Baltic states(already in NATO) are as close to Moscow as Harkiv. And defense wise Russia will be much weaker in the decades to come with an isolated economy. Putin wants a poor desperate and isolated North Korea like country, he doesn't want a prosperous Russia -- prosperity is not too compatible with authoritarianism.
People like to post this, but Dugin is mostly irrelevant in Russia, and I doubt he had any influence on Putin's decision making. Putin's imperialism is of his own biographical origins.