I do not want to respond too harshly, but the question was whether it takes one to tango. And it does. Germany did not need Poland's permission to invade. All Germany needed is a moment it considered favorable. Everything else is an excuse used for public consumption ( and if you look at Iraq and Iran, the parallels become obvious ).

As for the aggressive actor part, I will leave it for now ( it does not add to conversation and since I am not a historian, I can't authoritatively say that comparatively speaking Poland was the nice guy on the block ).

They also left out the part that Poland invaded and took exactly back that which Czechoslovakia had invaded Poland and taken only a few years before during WWI.