So you're saying if Hilter or whoever decided to make an alliance with Poland, that would provoke France or Britain into a war? I thought that the Brits and the French were bending over backwards to avoid a war, enough to allow the dismemberment of Czechoslovakia...that doesn't seem right, maybe I'm misunderstanding what you mean.
Afraid so.
The Idea is that Poland and Germany form some kind of long term pact, which Germany isn't really intending to honor. So, after Germany finishes Czechoslovakia, and Germany turns on Poland, the UK and France REFUSE TO HELP Poland because of its past abuses.
The idea is that while Germany is almost certainly going to get a war sooner or later with the UK and France, it need not be over Poland--if the Poles start to look like bad guys to France and the UK, war would be much less likely to happen over Danzig. Poland needs something on the level of a coup d'tat and a complete government screwover to ignore Danzig--which is not really in the cards.
So, the idea is that the UK and France find an alliance with Poland unpalatable, because Poland has positioned itself badly--gone too far on Germany's side--for them to get involved. A long shot to be sure, but certainly believable. That said, France and the UK would never tolerate German ambitions in Western Europe. War Delayed, not war denied.
This is an idea of Germany just plainly outmaneuvering Poland in diplomacy. It would be similar to Germany making a move against Italy--The UK and France would probably leave it alone. Italy is really screwed if Germany goes after Italy. Poland, OTL, didn't fall for the bait, and they were canny enough to pick the eventual winners of the second world war, although they really didn't win it themselves. There was a plan for Poland to Grab Lithuania in exchange for the Polish Corridor--if that plan had actually gone down, Poland would get betrayed and the UK and France would shed no tears.
And as for the UK and France--it was actually a matter of considerable stress, where Chamberlain and Daldilier might well have been acting against the collective will of their people. One thing is for sure--the British People at least would never accept a second Munich, particularly after Hitler broke it so blatantly. So, once the UK and Poland buddy up a war against Poland is a War against the Allies. Now, its this "buddying up" that can be averted. That, and perhaps the possibility of Poland's government completely collapsing (which might not be ASB but it's close, the Military Junta that ran Poland wasn't exactly unstable.)
As for Poland handing over the Corridor--this is again, not ASB but close. Perhaps if the Soviets hit Poland from the Back and Germany announces that its taking the corridor one month later, that might work. But Poland has a long history of being abused by its neighbors--they aren't Czechs--and they are going to fight Germany if they possibly can.
In short: Poland giving up the Corridor without a fight is nearly ASB. But the UK and France not backing Poland is at least plausible with the right setup.