s0ul0: Please take the time to read this
But honestly, how hard is it to change the colour of the player. DP2 isn't so much of a game that requires stealth or blending in to the surroundings...
And I'm quite sure changing the colours wouldn't affect the colour-changed people.
Anyone with a big disability in sight probably shouldn't be playing on the computer... that's where they're seriously handicapped. But just being red-green colourblind, is really light.
Other traits like slow reaction time or good hand-eye-keyboard coordination, these are different - they're not disabilities.