The infra red space telescopes are positioned out of the sun ('behind' the earth) in order to keep cool. However, there's still the heat from the electronics, and there's no way to get rid of that apart from by radiating the heat away. Black radiates well, hence colouring it black will keep the spacecraft cool.
In sunlight, more heat is coming in than going out, hence black cars get hot, and normal spacecraft are coloured silver (or similar) to make them highly reflective and bounce the heat off. (Even those spacecraft will often have dark surfaces on the other side in order to keep cool.)
I'm guessing that the Blackbird SR-71 got so hot with the engines, that painting it black would result in far more heat radiated than the sun would put back in. It's all a matter of balancing heat in and heat out.
The summary is a little wrong: "Because the light absorption level is so high, the super-black material will also keep temperatures down for the instruments it is used on." I think that should be "Because the heat radiation level is so high, the super-black material will also keep temperatures down for the instruments it is used on."