^^ I think the OP was talking about coconut water spoiling during a long ride. I do agree that you can get a week or two easy storing opened-but-sealed coconut juice in the fridge...
But regarding on-the-road spoiling, I think it would take more like 12-24 hours at hot temps (90-100) before coconut juice would start noticeably turning. It's pretty pasteurized. And even when it did turn the bacteria (or very possibly air-born yeast) wouldn't do much damage to you. Unless you had a very compromised immune system or if you had anthrax floating in the air.