Thanks for the cites. After reading all available info, here's what I've interpreted.
1. If a participant is fully vested, under the longest allowable vesting schedule, forfeiture under "bad boy" clause is not an option.
2. A plan may required an employee to complete/execute an employment agreement or other contract prior to allowing the employee to become a participant. This approach would not allow a forfeiture under the bad boy clause but would potentially create other legal recourse for the employer.
My conclusion: A bad boy clause can only work in a situation where a participant is not vested under the maximum statutory vesting schedule.
Am I missing anthing here???