I think we can agree that it has not remained registered in CA for 44 years. But just for example, my TR3 was stored in CA (just a few miles from my house) for nearly 30 years. I'd still call it a "CA car", even though it did have some significant rust (likely from being driven near the beach).
And the laws have changed relatively recently, I believe there was a time when you would not be allowed to keep the black plates if the old registration had lapsed. That plate is several years old at least, judging by the leading digit. (CA plates are not necessarily issued in sequence, but they are made in sequence. The current leading digit is '6', so those plates were made some 50 million plates ago. The leading digit was '1' in 1980.)
Modern plates use reflective paint, which makes them easier for the CHP to read at night; but the black plates did not.