The virus can survive for a short time outside of a host, but like most viral infections, it needs cells to infect, and quickly, the Aids cells themselves have a moderately short coherent life with which to find and infect another cell. In a human host, this is plenty of time, however, in this situation, I don't think there would be much threat unless you get a situation such as the Hep-B case in Israel, which came from a piece of bone from the suicide bomber getting imbedded in a bystanders skin, carrying Hep-B. This COULD cause infection if the bomber had been suffering from Aids or any other number of illnesses
Personally, I'd be far more concerned with the number of airborne agents a bomber could carry, which would be thrown far and wide by the explosion.
