Why so important to prevent a stall at the root of a swept back wing??
I think this may be confusing the generally accepted idea that it is important to prevent a stall at the
tip of a swept back wing.
If the tip stalls before the root, lift will be lost from the aft portion of the wing. This will produce a pitch up which will tend to exacerbate the stall.
On the other hand, if the root can be made to stall first, lift will be lost from the front portion of the wing. This will produce a pitch down which will tend to prevent further stalling.