Actually, it's not hard to prove at all. If a class action suit was brought against the board for breaching their fiduciary duty and unjust enrichment, all of their actions would be looked at under the lens of "what would any other company have likely done in this same situation?" If it is usual and customary to PR certain things that were not PR'd and the BOD got unjustly enriched from it later based on them knowing things that the shareholders to whom they owed that duty did not know, well, that's pretty much case closed.