This is troubling: A.Q. Khan, the Pakistani scientist who sold nuclear secrets to Iran, Libya, and North Korea, was released yesterday from a five-year term of house arrest after a drawn out legal battle failed to result in his conviction. The United States, which discovered Khan's smuggling ring more than five years ago, has criticized Pakistan's light treatment of criminals involved in nuclear proliferation. "Too many network members are getting off with little punishment," complained David Albright, a former UN nuclear inspector familiar with the network. "The busting up was handled far better than the rounding up."