Thought I'd report back for those who are interested. Arms Unlimited responded back to me with the following:
"We are not a licensed importer, we don’t do any importing. The import marks are all done in accordance with ATF rules, so that is what the importer did. We are a distributor for the imported HK firearms and will continue to offer rare HK German imports so keep following us!"
So this begs the question, who is the actual importer? Well, according to ATF rules, it is "HKI." Hmmmm, okay.