I am guessing they are leasing them back because it was the...

I am guessing they are leasing them back because it was the fastest way to create a buyer (the finance company).
I don't think they could contemplate hooking them up to sell power to the grid - I am guessing it would cost too much to generate too little.
They might also have done it to liquidate any easily disposable assets making them less attractive for a receiver to support the idea of winding them up.
But, most likely it just raises some cash to keep paying wages and expenses while they work through more options for refinancing the project.

At the current market CAP somebody could probably buy the whole show for (say) $10 to $20 million tops.

Question is - why would they?
NRZ have done a lot of the heavy lifting working through time consuming preliminaries for developing an ISG fueled Urea Fertilizer plant.
Yes, there are still a few billion left to spend to get it into production, but they have shortened the time frame by 3 to 5 years.

However, there must be some other show stoppers.

And letting the company slump in to suspension was possibly a strategy to stop the price falling to $.001 - at that price it might have been possible to take it over and strip the assets for good profit. With the generators gone - less so.

IMHO