That is not the origin of the term. It comes from a desperate act of defense intending to leave an attacker you can’t beat in open combat with nothing to forage or pillage, forcing them to rely solely on their over growing supply train. Most armies would only ship in supplemental food and supplies while largely living off the land.

Um, they very much did make promises to that effect. Neither were in good position to actually help the Poles when push came to shove, hence the Phony War. Brittain did some good with their navy, but neither could get enough troops to where it mattered to help, so they buckled down on ramping up their own war efforts at home to better mobilize. Did they fo it out of cowardice and throw the Poles to the wolves, or out of necessity because they would have been overrun had they over commited? That’s a question that has been the subject of much study. But they both very publicly and loudly commit to their defense, they simply failed to meaningfully uphold that commitment.

I mean, the obvious answer is instead of trying to divvy the sovereign nation between them, they should have stood up for them and defended them when the Nazis rolled in. Barring that, they should have liberated them, then left them the fuck alone. Even a stopped clock is right sometimes, this comparison is pretty clearly silly. They weren’t lamenting the lives of Nazis lost in the battle to push them out of Poland. They were lamenting the lives of the Poles after falling under the Russian boot, after the battles were won.