I think, looking again at the passage I quoted, what was proposed (and agreed ITTL?) was that the German Armies would mobilise as planned then shift towards the East. The move Eastward would be as formed Armies and via the rail network. If - and I stress if - the French attack soon enough, then the move (not mobilisation) can be cancelled and the Germans can march/rail to meet the French. There would be delays but not necessarily a breakdown in order amongst the Germans. Something akin to the Austrian bungled deployment of their 2nd Army in the opening stages of the Serbian Campaign, but dealt with better due to superior German organisation.
There only needs to be sufficient delay to allow the French to strike first.
As far as a POD goes I really like it for no other reason than it is tight into the events and needs no deeper changes that incur the wrath of butterflies. It is plausible and as far as I can tell grounded in actual events as they unfolded. General Hermann von Staab, head of the German railway division, argued that he could wheel the armies East if ordered. Here I think you take away 1st, 2nd and 3rd from the right-wing, leave the 4th in position to defend against the now obvious French rumblings to use Belgium. You might get the Corps up on the coast pulled in to strengthen 4th Army since it will be assumed the BEF is not mounting an invasion. As the troops deploy East and the war gets foggy the French might go for it as they assume Belgium will yield. Germany and Britain exchange notes and protest as France strikes. Damned un-sportsman like.


