I'm not sure what you mean that effort was put in to keep the anthrax from spreading. This stuff wasn't your grandmother's anthrax. The spores were small enough to pass through NATO biofilters. They were mixed with high levels of silicon, which apparently made them better at infecting the lungs. Sandia tried and failed 58 times to reproduce the high silica content, apparently. If anything, it sounds like the anthrax was intentionally designed to spread better.