I guess that depends on your understanding of "vesting" - and my understanding may be faulty.
As I understand it, if I leave the business before the vesting I get nothing. When the stock vests it becomes mine.
A lock down of the stock then means I can't trade it, but it remains mine (regardless of whether I stay or leave.) Once the lock is lifted I could sell it.
That could be easily fixed by requiring all executive and board members' stock to be held for, say, 3 years after vesting before selling.