Pretty much nonsense IMHO.
The Manstein plan was
NOT about a "
pincer movement" but about the "
Sichel-cut", if I might remind you.
And yes, Manstein had learned from Moltkes mistakes in exactly
NOT to flank the french and wallies but to lure them into a mousetrap with the Ardenne advance as the bar to snap on their neck (what pretty well worked IOTL).
To lure them into this trap it
should exactly look like a Schlieffen/Moltke-plan-redux. What it did to the allies, why they acted like they did IOTL. So ... with sparing the Netherlands it would look even more like a Moltke-redux. I don't see why ITTL they should react any different from IOTL.What overstreched front ?
If you might have a look at the
wiki-site about the western campaign, you will see, that there were no french forces in the Netherlands.
Their front wiht the germans won't be any shorter or longer than OTL.
Therefore the claimed by you "benefits" for the wallies won't exist ITTL.