I don't MC is a coward. The FMC is. Its easy to be tough when you have power. In the MC's world, she is just as dangerous as the sleazy lawyers but she, unlike them, thinks she's some hero. She used the recording to get the lawyer of her back, but not to put him down permanently, because that would cause real trouble for her.
But as another commenter said, he is holding a lot of card and just does not know it yet.