I have no way of investigating something I was not supposed to find out about in the first place. Given Wikipedia's culture of retaliation against anyone who speaks out, I am unlikely to find out more, but it did seem credible. These agreements are becoming more common, for instance here a female employee wanted to get out of her non-disparagement agreement but Angel List said no.
https://www.nytimes.com/2017/07/21/technology/silicon-valley-sexual-harassment-non-disparagement-agreements.html Also the internal Google gender manifesto that was just leaked "Until about a week ago, you would have heard very little from me publicly about this, because (as a fairly senior Googler) my job would have been to deal with it internally, and confidentiality rules would have prevented me from saying much in public.But as it happens, (although this wasn’t the way I was planning on announcing it) I actually recently left Google..."
https://medium.com/@yonatanzunger/so-about-this-googlers-manifesto-1e3773ed1788