That's his propaganda narrative. There may be some truth to it, but he confessed to more truth than that when he gave his speech this week saying he thinks Russia is entitled to its pre-USSR empire, which was about 17% of the world's land (it now has 11% even with the losses from the USSR).
I suspect Rachel Maddow tonight had a more plausible motive, that Putin has crewed up Russia so badly, with a low per capita income, that he can't stand to have neighbors who Russians relate to seen as in a much more successful country, showing them how badly Putin runs Russia.
As well as Putin's long-time resentment over the fall of the Soviet Union among other motives.
Even if there was a nugget of the issue about concern about Ukraine and NATO, Ukraine wasn't going to be joining NATO for at least years to come, with a lot of opposition to their joining from NATO members, suggesting Putin's motive is simply aggression and NATO is one of his excuses, like his false flag attacks. Regardless, it gives him no justification under the UN charter.