Question - Why are covenant bosses in red?

Red is suppose to be the color of everything supporting Swords of Sanghelios (SoS)
And SoS is the faction that belongs to arbiter and is sided with humanity…
So, why are all warzone’s covenant bosses wearing red armor or sat in red vehicles?
I know that all of Arena and Warzone is a simulation within the universe, but why would the UNSC train spartans to eliminate any SoS vehicles or soldiers?

Maybe SoS are also participating in the simulation like we are, althought it also would sound wierd…

I think the color is just to highlight the fact that they are bosses, because it isn’t quite the same red as Swords of Sanghelios equipment. SoS vehicles and armor are a more orange-red while Warzone bosses have a crimson red appearance.