Gobekli Tepi is an interesting site, but doesn't really seem like 'advanced civilization' relative to later developments:
> "Göbekli Tepe is one of the most important archaeological discoveries of modern times, pushing back the origins of monumentality beyond the emergence of agriculture. We are pleased to present a summary of work in progress by the excavators of this remarkable site and their latest thoughts about its role and meaning. At the dawn of the Neolithic, hunter-gatherers congregating at Göbekli Tepe created social and ideological cohesion through the carving of decorated pillars, dancing, feasting—and, almost certainly, the drinking of beer made from fermented wild crops."
(2012) "The role of cult and feasting in the emergence of Neolithic communities. New evidence from Göbekli Tepe, south-eastern Turkey", Dietrich et al.
The Younger Dryas is a well-studied period in paleoclimate science and the evidence of an impact triggering it is pretty scant, see this from 2011:
https://sci-hub.se/10.1016/j.earscirev.2011.02.005
> "In summary, none of the original YD impact signatures have been subsequently corroborated by independent tests. Of the 12 original lines of evidence, seven have so far proven to be non-reproducible. The remaining signatures instead seem to represent either (1) non-catastrophic mechanisms, and/or (2) terrestrial rather than extraterrestrial or impact-related sources. In all of these cases, sparse but ubiquitous materials seem to have been misreported and misinterpreted as singular peaks at the onset of the YD. Throughout the arc of this hypothesis, recognized and expected impact markers were not found, leading to proposed YD impactors and impact processes that were novel, self-contradictory, rapidly changing, and sometimes defying the laws of physics."
It does seem to sound a bit like 'the lost civilization of Atlantis was wiped out by a cosmic impact' fairy tale. Also the claims of a 'cover-up' are pretty silly.