There is no legitimacy for that. I don't see any reason whatsoever to argue against this, or underscore Putin's opinion because they are "underrepresented".
If Selenski and the USA try to bring the Ukraine in its current borders into NATO, while already arming it up and supporting a hardliner course which being directed, very directly, against Russian people and interests, its noteworthy, regardless. Because its a reason for war. Even more so if they cut off Crimea from water supply, banning all pro-Russian media and persecuting pro-Russian citizens, doing various kinds of mistreatments and war crimes in Donbas, like the mentioned hunger blockades, shelling of settlements, killing of leaders, tortue of prisoners and all the time threatening that Russia can't do anything, but just watch the opponent building up forces, until it hits its interests and allies with all the more force.
Then ignoring all the hundreds of thousands of pro-Russians which live now for years as refugees in Russia, because of the Ukrainian unwillingness to compromise. The corruption in the country and its aggressiveness towards all people which don't support the war, its neglect for the civilian lifes and how they drag men into service as cannon fodder.
The list might go on and become longer and longer, many things I don't even know as of now, and which all make clear that we are not at this point just because "Putin went crazy". At first I thought it was totally wrong what he did, and
I still think its not justified to escalate things to this level, but there is a problem: What were his alternatives? Like I said, Ukraine was on war course, no matter what Russia did, they just build up their force to kick Russians and all pro-Russian/ethnic Russians which don't support the regime out. They want to take back Donbas, they want to get even Crimea back, with NATO support, they're unwilling to accept any compromise and just got stronger in their determination the last years.
If Russia would accept all that, all these catastrophic developments against Russian interests, they would still have a problem with Ukraine, because in Ukraine, all the oligarchs and their Western service agents with anti-Russian goals will build up a propaganda division, which will try to infiltrate Russia itself. That's pretty clear from the whole outline of it. Ukraine would be not just a military threat and problem, a great loss to the prestige and cause millions of Russian refugees, lost bases and positions, material wealth and resources, but it would stay a thorn in current Russias flesh all the years to come.
So what were the Russian options? Seriously, they were running out of options, because they got cornered by the unwillingness of the Selenski regime and the USA to accept any compromise. And that's why Russia did "overreact" and invaded the country. They were pushed to it, any objective observer which is able to consider geopolitical and strategical facts of the conflict will have to admit that, if being honest about it. In the above linked video, Mearsheimer did predict it 2015, that Putin won't invade Ukraine, only if being pushed that far and it might be a catastrophy for Russia - but that was the plan! And the USA and the Selenski regime just added one provocation after another, one push after the next, and no compromise in sight. Its an act of sheer desperation that Putin did resort to a full scale invasion. And the Selenski regime doesn't prove him wrong, because they just step up on the escalation ladder as far as they can and try to drag the whole world in this conflict. With people which act that way, show absolutely no sign for being ready to come to acceptable terms for both sides, you can't negotiate with.
Like I wrote from the start: I hope they can change the course of events, but this would also mean for Selenski to take himself back and not as important, but for that he is, quite obviously, by all his actions and appearances, too much of an egomaniac and self-promoter. Which is exactly why this situation is so dire.
These two regimes are for sure both not easy partners for peace talks, but some way they must get together, because what's the better alternative?