The alternative to not “carving up Poland” was to not sign the mutual non-aggression pact and essentially enter into war with Germany before it thoroughly fucks up Britain and France. Britain and France would be quite delighted if Hitler pursued that course of action. I’m pretty sure theyd even withhold any meaningful military assistance to help things along while Hitler makes his run on Russia, for the same reason Stalin did. In fact they sorta had done that already by refusing to enter into a pact against Nazi Germany.

You can’t reason about geostrategic considerations in terms of moral high ground. Those dudes were dealing with a very dangerous and volatile situation, and the decisions they made were literally matters of life and death for their respective peoples.

That’s not to absolve anyone of guilt, but if you’re going to be an armchair quarterback, do yourself a favor and study history a bit more thoroughly. At that negotiating table any of us today would have made the exact same choice.