How to prevent curdling in a local vegan coffee creamer- aka- Post Apocalypse hippy coffee creamer? Sorry, I got a few questions here.

1) I was at a vegan, locavore restaurant and their soymilk curdled in the coffee. Why did it curdle?

2) I thought, gee, they should use something like coconut milk, but that would clash with the (east coast USA) locavore them they have going on. So what will post-apocalypse hippies use in their coffee (or coffee substitute) for creamer? I've successfully made nut milk out of pecans and walnuts-- haven't tried it with coffee yet to see if it is curdle resistant, am I overlooking any options?
Was the coffee highly acidic or possibly salty? Coagulating agents that I know of consist of apple cider vinegar (which I personally use in my tofu making), magnesium chloride and calcium sulfate. Indeed, according to Wikipedia the common coagulants are salts, acids and enzymes.

Not being a coffee drinker I can't say this has ever happened to me. My boyfriend drinks coffee and I don't think he has ever experienced this, so it might be specific to each coffee. I have had soymilk coagulate in a cocktail I had once, but never when I make soy white Russians, so it must have had to do with the other ingredients in that drink, which have been lost to my memory.

Off topic, but what restaurant were you at?