Time contrast

This is the question :

I am confused between choices C and E. I am one with the logic, the time contrast. But as in E, he can be construed to be a coward since he does not stand up/ execute on what he promises. What is the loophole in this logic ?

the clue for blank(i) is in the lines refusal to compromise (means he is rigid) after initially agreed to negotiate a settlement (he is flexible i.e not rigid)

Also, cowardice means “lack of bravery”: which isn’t supported by any word in the sentence