A party put under duress can hardly be considered to be fully cooperating.
He apparently did fully cooperate with agreeing to a confidentiality agreement--he was not under duress to make that agreement--he had other options.
He simply could have appeared in court and asserted that there was no justification for the charge of assault/violence on his part which was given in the application for the Protective Order. He could have forced her to provide evidence of his prior assaultive behavior--which he tells us she didn't have, and would be unable to provide. And she apparently had not even testified to any assaultive behavior on his part.
So, did he respond in court to her allegations at a Protective Order hearing? If not, why not? That was his other option and, particularly if her allegations about him were false or could not be substantiated by evidence, it might have been the better option. If he didn't appear in court, to contest her allegations, he would have been tacitly cooperating with her desire to obtain the Protective Order.
We may differ in how we see being "under duress" or see being "fully cooperating" in this particular situation. If he had options, as he likely did have, he wasn't "under duress" to choose one option over the other--he didn't have to agree to the confidentiality agreement. By agreeing to it, I see him as being "fully cooperating" in an arrangement he felt was in his best interests.
He went along with what her lawyer wanted and is now complaining about it after the fact. He didn't have to allow himself to be manipulated in that way--he could have responded to her allegations in court, and further pointed out, in court, that she was trying to use a false allegation of assault to get him to agree to a confidentiality agreement. Complaining about it now, and complaining about how she used the legal system to her advantage, seems rather pointless. He had the option of handling it differently at the time.