Executives aren't able to time their sales of stock to events and they shouldn't be able to as it would lead to more manipulation. It is likely the sale of stock was planned ahead of the layoff announcement timing.
the only time this really makes sense (in my head at least) is selling prior to something that KNOW will tank you stock and make your shares worthless. If you just hold... sure you're making a decision to not sell, but other than looking VERY VERY bad to employees on the timing of things... the stock went up, he sold....
now if he sold a boatload of stock before a horrific earnings report... thats another story