First, CHC supplies 95% of the expat Captains for the operations in Thailand, 27 to be exact. TAS is the National partner that's required for CHC to operate in that particular country. TAS gets to provide copilots that are trained by CHC and spray paint their pretty logo on the side of the aircraft and that's it. Much like ACN in Nigeria, Awan Inspirasi in Malaysia and the list goes on....................
Second, who gives a rip what company shirt the two security guards wore. They were both shot to death while guarding a CHC compound with CHC pilots inside.
Third, the majority of the Thai National pilots have been wary about the move for over a year now due to the local Mafia and crime in the area. If it was a past argument with an employer why was the other guy shot? I'm sure it's not a great feeling to be on the base in the middle of nowhere, 50 km from the nearest civilization with this crap happening at the front gate.