Exercising the shares would not be a prudent business action. If they wanted to act, they could simply let them expire and go to RVX proposing a financing that would cover the debenture and more. For it they would get more shares plus even more warrants than they let expire at a much cheaper exercise price. 

It is much like major insiders that have input toward option grants. If the exercise is too high they just let them expire and issue more at a lower exercise price. The big guys don't lose. The fact the price dropped enough to make the exercise price too high probably means that they didn't do a very good job and probably never earned replacement options but merit isn't how those awards are decided.