Why Security Guards for Screening Covid-19? Well, the most straight forward answer, without getting involved with conspiracy theories creating to this pandemic, would be that they are there to control access to the screening areas as well as to be there in-case of any protest action or unruliness by patients being tested, especially if a positive result is revealed on a patient unwilling to accept this screen tests.
One thing where must learn and know, which the conspiracy theorist is trying to use to back up their theories of a coverup, is that these guards are not there in any way to do or assist in the medical or clinical side of any of the screening tests itself.
The closest they will get to clinical would be the temperature tests when entering the area, using a handheld device and or the administering of sanitizing liquids for your hands.