Unfortunately, it can never be “proven” that this is some sort of artificial object. Unless of course we receive some sort of message from them. Other than confirmed contact any speculation that we make in regards to what it is, it will only be just that..speculation. What I find most facinating is that we mostly assume that no other civilatiom that may exist among the galaxy has ever tried to contact us and perhaps we just missed the phone call. The technology that is necessary to “pick up the phone” so to speak has only been around for the last 60 years. Hell the inadvertent transimitions we have made that have waddled off into space has yet to even reach the closest star to be a possible candidate for life. We may be long gone before it ever does. Plus you have to consider the fact the light variations that have just been measured is over 1500 years old…this isn’t real time. It’s like watching a live TV show with a 1500 year delay. So as far as we know or possibly could ever know is that this was an unusual phenomenon that may never occur again. I am by no means a pessimist in regards to us being the only intelligent life in the universe ( which it is my firm belief that it’s a mathematical certainty that we arent) but Fermi may have made it very clear that our possibilities of ever actually finding proof lies locked away in the laws of the universe. With the exception of a few current quantum possibilities, by our current understanding we may never know. Fingers crossed, we may just get a visit one day.