A fun criteria for disclosure might be:
If the information is so "material" you might not want to disclose it, it is sufficiently "material" for its disclosure to be required.
Why would a potential partner of EDT not want the content of discussions to be public?
So other companies which might be interested cannot offer more favorable terms.
Why would a company's management team (EDT) not disclose its discussions with a potential partner? To not get the better deal...? So why would that management team shy away from the prospect of a better deal? Maybe members of that team or some entity having control over them are looking for some more "direct" sugar to sweeten the deal.
There are always interests around that do not care for a fair market. It also happens that those interests carry more weight than our institutions.