The article in the OP is explicitly talking about US involvement. The US and NATO are 'in there'. If NATO isn't in Ukraine, it was hardly ever anywhere.

Arguing that NATO isn't involved seems to be either disingenuous or naive. It accepts NATO's PR at face value and in opposition to the practical reality. NATO/the US tends not announce it's clandestine work in the tabloids or the broadsheets, especially as it happens but it does admit it sometimes, if you know what you're looking for. In the case of Ukraine, it's not even hidden. They've been bragging about how much weaponry they've been sending and how much they've been involved in training and instructing Ukrainians how to fight.

Was the US involved when it trained and funded Saddam, Bin Laden, or the Contras? Of course it was. Ukraine is another example of how the US gets involved without 'getting it's hands dirty'; although I've yet to meet anyone IRL who doesn't think the US has the bloodiest, grimiest hands of all. The only question is whether people think it's a good thing or a bad thing. The fact of it is not open to dispute.

I'll struggle to accept any argument that splits hairs over what counts as involvement, I'm afraid. It boils down to semantics without addressing the crux of the issue.

I'm also struggling to see why more visible NATO/US involvement would require Russia to admit defeat until it's been defeated. Unless you're implying that NATO would wipe the floor with Russia. That doesn't seem right for two reasons:

1. The best minds and the resources of NATO have been demonstrably unable to stop Russia so far and
2. If Russia looks like losing, it has the nuclear option and shit gets real messy real quick and it's lose-lose for everyone