No doubt a single X meets the legal requirements but a series of Xs for the first few hundred metres wouldn't exactly cost a great deal and make the situation more obvious.
And I notice on that photo that the single X is offset from actual centre line. It's 15+ years since I flew professionally so maybe I should shut up. But it does strike me as odd that the symbol isn't on the centre (or extended centre) line precisely where a pilot looks when landing.
I would say again, it was not a "closed runway". The piece of new tarmac in the place, were there was no runway before is not "closed runway", because it was never "open" before, not in any charts, Jeppesen or maps.
They did, what they could, taking into consideration, that multiple layers of concrete and asphalt were put on top of each other, and putting crosses all the way down on every layer would be little troublesome.
Also on the image you can see, they are still adding width to the left side of the tarmac, so nobody actually knows, where the central line is...