Isn't this analagous to a 403?

Technically, the client did err, as it performed a request that is not legally permitted in its jurisdiction. For example, this response could be used for geographically-limited resources (such as BBC iPlayer), which means your client erred by not being in Britain.

If it's a takedown of some kind, your client erred by being subject to a government that ordered you unable to see the resource that you requested. The 4xx code fits, in this case, as 5xx implies the server made a mistake (it didn't).