Though germs were not understood, there was an understanding of the communicability of diseases and the existence of diseases was also well understood. They also had names for various diseases. And in the case of smallpox, blankets were purposely infected and distributed to indians as early as the year 1763:
These stories are reported, for example, in Carl Waldman's Atlas of the North American Indian [NY: Facts on File, 1985]. Waldman writes, in reference to a siege of Fort Pitt (Pittsburgh) by Chief Pontiac's forces during the summer of 1763:... Captain Simeon Ecuyer had bought time by sending smallpox-infected blankets and handkerchiefs to the Indians surrounding the fort -- an early example of biological warfare -- which started an epidemic among them. Amherst himself had encouraged this tactic in a letter to Ecuyer. [p. 108]
This certainly casts doubt on your assertion that the concept of using disease as a weapon of mass destruction was unknown, nor that its indiscriminate nature was in doubt.
I have read of sieges during which the carcasses of dead horses would be catapulted across barriers to encourage disease among the besieged. I don't know for sure if this *practice was used in post-Colonial America. Cities during both the Revolutionary War and the Civil War would come under siege and would be bombarded with heated shot with the sole intention of starting fires to drive the occupants out. This seems pretty indiscriminate to me and yet it would have the desired effect of defeating an enemy.
An enemy. These are actions of a nation at war, which could be said to be the case in the use of biological agents against the Indians.
I would like to keep our focus strictly to individual rights as detailed in the Constitution and Bill of Rights.
You are certainly more informed than I regarding the use of smallpox as a weapon. Jenner's development of a vaccine came in 1796, so I am puzzled as to how one could handle smallpox infected blankets without incredible risk to himself or the people he was trying to protect.
I disagree with your distinction regarding individual rights versus national action against an enemy. The whole point of the Second Amendment is that the federal government can become the enemy of the people, use its control of the army to tyrannize the people, and thus the people must have the means to defeat the tyrants and re-establish a free state.
I also disagree with your claim in the posted article that a machine gun is of "slightly more questionable" justification with regard to target discrimination. Having trained on the M-16, I assure you that it does not belong among those arms which might reasonably be outlawed as being indiscriminate.
I am also puzzled by your assertion that an anti-tank rocket is less discriminating than a cannon shooting ball shot.