回复：这是法律咨询，不搞政治 I appreciate it!!!

the issue is how he got green card in the first place. Under U.S. immigration law, membership in a communist party is ineligile for green card unless they can prove it's involuntery, it's requied for the job or by the law, or you have left the party for 5 years. If he didn't disclose he was a party member when he applied for green card, CIS will consider that to be misrepresentation, and they can even revoke the green card.