Genetics of ancient people do have gaps. But both archeology and time/transect of genetics firmly show people with farming with genetics from Anatolia arrived in Britain in the time frame Laird is seeing in his comparative cosmology analysis.
Orkney is one of the most genetically-diverse places on the planet - people from all over seemingly arrived there, and Atlantic ocean currents would lead a sailing vessel right to the island. The question isn't whether we can show that a group arrived in that era - it's whether what we see as major features there match the cultural practices of those groups.
In particular we should be concerned about elements that are unique to Orkney in the UK, such as Orkney barley, the Orkney sheep, the Orkney vole, the forms of architecture and megalithic structures - the burial practices found at the Tomb of Eagles. Likewise we should be concerned whether place names have sensibility in the language of a group.
In my estimation we have a candidate culture when those elements come together comparatively.