I see what you did there. Purple cloud of some explosion discolored him and made his red armor blue. Rite?
This is why bungie decided against making the armour in halo 3 fully customizable by players, E.G., like being able to pick colors in dedcals in a racing game.
It's a really bad color shift in the area around his legs, that's why the ground/air is purple and why there's no B.net link.