I'm sure there was something in the original contract that would not allow this - for obvious conflict of interest reasons. Tullow could have deliberately damaged HDY in order to buy the company cheap. I don't think this could happen.
The value of trading today is damn low considering what should be decent news. I think the market is just blowing HDY off because it will be facing bankruptcy before too long.
Now that the FCPA thing is done, and Ebola is under control, Tullow should be moving ahead. Those were the two "impediments to drilling" that they cited. If they start now they could be drilling before year's end. But, I think Tullow is a shitty partner so I don't expect any good faith here.