In FAA world, I don't believe there is such a thing as PICUS. It is a single pilot plane (C208) operated in a regulatory environment (FAR 91) that did not require a SIC; hence, the time is no different than being a passenger. IF you flew a leg as "sole manipulator" of the controls and were Commercial Pilot with Airplane Single Engine Land (assuming landplane) then you could legally log THOSE hours and credit them toward the ATP as PIC time. The insurance rules are irrelavent to the FAA. Check FAR Part 1 and Part 61.
GF