But my point is that if we implement a policy to rollback but otherwise not punish executives who sell stock right before an event like this (notwithstanding any actual other crimes related to insider trading that could be prosecuted separately; for example tipping someone off), the standard of proof becomes irrelevant.

Personally, I think the solution is to not allow executives to sell stock without publishing a schedule in which the first sale is more than 9 months from the date of the announced schedule.