No one has the right to declare years of work as obsolete!
AFAIK, the work you do can still be used and shared and used commercially. You just have to comply to NPL, which requires you to pay for copyright removal.
I have enough spirit to resist and I surely will.
Why not submit your awesome work as a pull-request into nopCommerce? Why create a fork in the first place? Nobody wants to invalidate your work. It is awesome. It looks absolutely great, no kidding. Why can't we work together?