Well, that article also says
This conflict is existential for most modern Western elites, who are failing and losing the trust of their populations.
This conflict is not about Ukraine. Her citizens are used as cannon fodder in a war to preserve the failing supremacy of Western elites.
which kinda sounds a bit lacking in the supporting arguments. But then again, the article leads with
Sergey Karaganov is a prominent Russian political scientist whom I have [...] interviewed many times as a window into Kremlin thinking.
so maybe it's just that, Kremlin thinking. And, in a way, it makes sense, if you change your viewpoint enough.
From the war angle, Ukraine alone obviously shouldn't be able to invade Russia. Not alone...
Mr. Karaganov warned for years about a potential conflict in Ukraine over NATO expansion.
we saw how deep Ukraine’s involvement with NATO was — a lot of arms, training. Ukraine was being turned into a spearhead aimed at the heart of Russia.
But it makes some sense in that if NATO wanted to start a land war in Russia, exactly in the way the probably feared a few decades ago, by aiming their armor divisions at Moscow, being able to use Ukraine would be a benefit. That's a bold "if"; I don't expect the people in the West would be really interested in that, but if one thinks in Cold War terms, and is paranoid enough, it starts to look scary.
The article also has this:
I am reiterating in most of my writings and public appearances that we should preserve freedom of thinking and intellectual discussion, which is still much wider than in many other countries. We do not have the cancel culture or impose the deafening political correctness. I am concerned about the freedom of thought in the future.
For what I hear from western media, it doesn't look like "freedom of thought" is that high on the priority list in Russia either.
So, I would perhaps take that article with a rather large crystal of salt, or as a report on the political propaganda. As a comment under the question says, political rhetoric doesn't need to be based on fact. And if you're in a country where the state controls the media, your arguments don't even need to be very good for the people to buy them, as they'll have a hard time finding contrary opinions anyway.
That said, Ukraine could be a problem politically.
Given how it's culturally somewhat close to Russia and was a major part of the Soviet Union, the fact that the people in Ukraine could oust a Kremlin-leaning president just by themselves, as happened in 2014, gives a bad precedent. If it works in Kyiv, who's to say it doesn't work some day in Moscow?
Not that it would necessarily be bad for the people in Russia, but any development of actual democracy would be bad for the regime. Hence, a threat, that warrants some action. Action that needs some rhetoric to justify it.