Not Equifax, Target, or one of several medical insurance providers?
Concern by company law departments probably is justified, though, since the shared information might include details pointing to a company's culpability, and therefore civil liability, in a breach. Such information should, and probably would, turn up during a lawsuit's discovery phase, but a government leak could help plaintiff attorneys know exactly what to look for and judge whether the discovery product was complete.
Indemnity for the companies, as it seems Krebs hinted, seems a bad idea; it might be better to require technical data sharing for all breaches requiring victim notification under state law.