aguaviva

And I encourage you to do so, because if you look at the actual event protocol it simply doesn't support what you're saying.

The bottom line is that whatever was said verbally at the time was understood by all participants to be part of the brainstorming process in the course of negotiations of what would eventually become the 2+4 Agreement. And simply put, this particular proposal did not make it into the agreement. As one notable observer put it: "It was tough, everyone knew that only what is written in black and white in the contract counts."

That's why Gorbachev insists (in an interview you can easily find) that even though he felt that NATO expansion was against the "spirit" of the negotiations, there were no statements about NATO expansion that rose to the level of a "promise". We also have Shevardnadze's equally stringent denial (per the sibling commenter), and strong counterweighing factors, such as Russia's greenlighting of the first round of ascensions (PL, CZ, HU) in the 1997 CFE Treaty, which by itself renders the "broken promise" theory unequivocally moot. And some notable language in the NATO-Russia Founding Act signed in the same year as well.

The war was at least partly instigated by our refusal to promise to keep Ukraine neutral and out of NATO.

That's a severe misreading of the article you cite in association with this statement. Simply put, that's not the language of the article, and that's not an implication it makes.

How would you feel about Russia making trade deals with Mexico, sponsoring pro-Russia politicians,

So far so good. Whatever one may feel about Mexico taking that direction -- it is after all a sovereign state. And while such circumstances would certainly be a matter of concern to the US, the idea that they amount to something in response to which the US would need to launch a full-scale invasion of Mexico (or that such a move could possibly be beneficial the US in any way) would, of course, be seen as batshit insane.

... and selling advanced military gear to them?, ... How would you feel if Mexico was attacking us with cruise missiles supplied and operated by Russia?

If this happened only after the US launched an invasion of Mexico as plainly stupid and unprovoked as Putin's invasion of Ukraine -- all rational observers would agree that Mexico would of course have a perfect right to defend itself -- indeed, "by any means necessary".

Including the procurement of advanced military gear of virtually any conventional description, from whichever source it could find.

Of course it's unrealistic to expect that the status gradient simply shouldn't matter. It's perfectly natural (and useful, healthy) to weigh what people say according to their status, to some degree. It's just human relations, as you say.

Where things become problematic is when their putative status becomes the primary or overriding factor. That is, "X is true (simply) because Y said so" environments. Or "You're just an L{N}, but I'm a L{N+k} so even though I don't actually know what I'm talking about, I don't have to listen to you" environments.

Those are the ones you want to avoid.

Except they didn't.

The footnote you cite describes Burns's concern, but not what actually happened: NATO rejected Ukraine's membership appliction in 2008, and Ukraine itself formally disclaimed aspirations of joining NATO in 2010, stating that Ukraine would remain a "European, non-aligned state."

And there the situation sat until 2014, when Russia invaded anyway, making any objections it might have had to Ukraine joining NATO instantly and forever moot.

This idea that the West was aggressively dragging Ukraine into NATO is just a soundbite you heard somewhere, but has no connection to reality.