Question on Polymorphic VG Wing

Don’t seem to be able to find anything on the advantages of adopting this configuration which was used on the Fokker/Republic Alliance D-24, Republic VFX

http://aerofiles.com/repub-vfx.html
http://www.dutch-aviation.nl/index5/Military/index5-1%20D24.html

proposal and some of Barnes Wallis’ VG designs. On the D-24, you have an aft area when the swing wing deploys.