Brown Coconut water safety issue?
The only thing I know is that sour water from the brown mature coconuts is horrible tasting but I didn't get sick from it. I would not keep the meat if the coconut water is in question. The meat is not safe from bacteria if bacteria has touched it.

Check out what organyx has to say here about the pink and purple color: http://www.chow.com/food-news/84067/is-coconut-water-bad-for-you/

I've found this site very informative in the past: http://foodbabe.com/2014/07/15/how-to-buy-the-healthiest-coconut-water-and-avoid-the-worst/