This explanation for how the find was dated makes no sense. You can't scientifically date objects to 15,000 years ago based on style or theme--scientists do radiocarbon dating, they aren't art historians who analyze aesthetic style or theme trends, and neither do art historians have any way of dating a style to 15,000 years ago. Of course it's Reuters reporting this, so who knows what Ouachi or the scientists he's citing actually said. . .
It helps tremendously that the "scientific establishment" believes civilization started 15,000 years ago.
Pick a date that is much older than that and you better have extremely good science to support it or the establishment will ridicule you as a quack and pull your funding.
Pick a date that is much younger than that and you might as well be digging up your grandmother's grave. Nobody wants to hear about it. It's not newsworthy, and there goes your funding.
But pick a date, say right at 15000 years that is what the establishment believes is the beginning of civilization and then you have the ear of the news, as well as the ear of the scientific establishment. If you introduce anything at all that's new, you better make sure that your work enables enough of the establishment to say "I told you so". And your funding's assured.