I'm glad you made a post about this.
I woke up this morning and dorked around the game a bit, checking things out. I noticed there was no colorblind option. I thought there might be somewhere else the option was. But, it's looking like there is none. It's definitely not the end of the world, but when you end up blowing away a orange colored friendly because you thought you saw the color red, it adds a HUGE degree of difficulty. This doesn't really have too much effect in the real-world, but when you are looking at a backlit monitor trying to display colors, it can be damn near impossible.
This is coming from FPS experience. COD games (before they added the colorblind modes) were insanely hard when teamkill was turned on. Instead of seeing a color and blasting, I had to look at the uniform they were wearing and ID the enemy from that. The addional time it took to ID a target and drop them definitely set me back in the leaderboards.
Maybe that could be the next difficulty settings in games.. Colorblind mode. All the friendlies are red, enemies are red, and quest NPCs can be red.
Easy < Normal < Hard < Extreme < Survival < Colorblind