I don’t really believe anything Putin says, I believe what he does. I think “protecting ethnic Russians” was an excuse to achieve his main goal, which was to keep Ukraine from joining NATO, and to resolve the dispute around Crimea.
I think he wanted a quick war, but Ukraine didn’t play ball and now he needs to save face to stay in power. So he desperately needs a win here, so he’s pivoting to Russian nationalism to stay in power because it’s becoming pretty clear that this war is going to drag on.
Idk, if he completely absorbs Ukraine, that puts him right next door to a very angry NATO. I really don’t think he wants that, he wants a buffer, and he wants Europe to get over what he’s done in Ukraine. I think he now sees that ship has sailed, and he can’t really back down due to local political pressure, so he has to keep going.