That's an interesting situation.  I'm not quite sure of the answer.  I vaguely remember reading some guidance about it years ago, but I don't remember what it said.

You situation is that the Marketplace does not have ANY SLCSP for your client's new zip code (because he moved out of State).  I don't remember what the rules are for that.

Was the health insurance used after he moved?  If not, the taxpayer may try calling the Marketplace and point out to them that he CANCELLED the policy, and they should issue a new 1095-A to show that.  I suspect that would be an uphill battle, and it may take a considerable amount of work and effort to try to convince the Marketplace to do that.  That is the best and most correct way to do it.

Otherwise, I might just leave it as-is, unless it creates additional credit for the taxpayer.