Just thinking outside the box, if they are as you say, and the rest of the workers have been carrying them, maybe a 3rd option is distribute their stock to the

Just thinking outside the box, if they are as you say, and the rest of the workers have been carrying them, maybe a 3rd option is distribute their stock to the remaining employees (maybe according to contribution but everyone gets some)? While concurrently making it super clear it was due to performance. Perhaps make that distribution immediately vest too. Then no one can claim you're firing just to avoid vesting stock.