No, you're thinking of something else. Smallpox is an aerosol spreader. Those stories Ward Churchill (remember him?) used to write about infected blankets giving smallpox to the Indians were pure fantasy, it doesn't work like that.
The real difficulty is twofold: (1) we don't have stockpiles of vaccine against the normal, wild type of Variola, and (2) nobody has much of anything against the weaponized type except presumably for the guys who produce it because they're the only ones who know what modifications were made. Nasty, nasty stuff - very low threshold dose, some people even claim one virus particle but that would be impossible to determine with any degree of confidence. The variation in immunity you see in a normal population may not be the case with the weaponized versions - think Ebola and you'll get the picture. The stuff is very adept at picking up pieces of the host genome, which is why it's so attractive to bio-warfare.
Good sanitation practices can certainly restrict its spread, though, especially if the cordon is tight enough and the infected population small enough. But I do think that even if the conventional vaccine confers only a partial immunity, it's worth producing in usable quantities. Just my $0.02.
The bed bug connection to smallpox was discovered in the late 1920s. It was recognized as the reason that those caring for family members with the pox at home were not getting infected at the high rate that nursing staff and patients in hospitals were.