Because none of the 1000's of shareholders that COR is claiming that did not respond, were notified about COR lawsuit. If they say the responses did not address the illegality of the dividend, that's because none of the shareholders were informed about the COR lawsuit. If all shareholders were informed, may be some might argue the legality of the dividend issue.
You cannot pick and chose what 8 shareholders wrote, when you claim 1000s did not respond. They were never notified.