To debunk your argument let's take two cases:
1) a private person living I western Nebraska having a mustard gas bomb
2) a person in Manhattan having a cannon
Two swings, two misses (and way too easy)
1) Whether in a rural area or not, a mustard gas bomb cannot be targeted against an aggressor alone. "Know your target and what is beyond." Even if the rural homeowner might, in some bizarre case be able to use mustard gas against attackers without obvious risk to known neighbors, he cannot assure that the wind doesn't shift after deployment, or that some innocent person doesn't come along after he has released the chemicals and before they have dissipated. He cannot target only aggressors.
2) Manhattan is a major port and one can easily conceive of a privately owned cannon being put to use against an invading naval force. Pointed at those sea-faring aggressors by the local militia, the cannon poses no practical risk to the innocent persons not being targeted. A cannon ball fired will go where aimed and within a second conclude its flight.
WMDs cannot be targeted against attackers alone. They are indiscriminate killers and can readily be considered immoral.
Do you disagree with this? Or do you just want what government has? Two wrongs make a right?
Looked at other ways:
1) Lacking proper maintenance, the mustard gas bomb degrades and releases the toxic chemicals entirely without control. We came very close to this at the Tooele Chemical Depot west of Salt Lake City.
2) Lacking proper maintenance, the cannon rusts into a harmless pile of iron oxide.
The benefits of owning a WMD are virtually zero since they can't be used defensively in a moral fashion. The risks of owning them are tremendous and extend far beyond one's personal or family matters. The risks come not merely from improper use, but from storage requirements as well. The risks of improper use are horrific and almost impossible to defend against or mitigate.
The benefits of owning guns (even really big guns) are obvious, the risks are far more manageable and contained with nearly zero community risk of lack of maintenance. The risks of improper or criminal misuse are readily mitigated.
A guy opens fire in a café with a 50 cal or even 20mm machine gun and all it takes is a .22 round placed properly to end the threat.
A guy detonates a WMD in that same café and there is no ending the threat. A city block, or 10, or 100 are eliminated or everyone within them dies. Lethal aftereffects may linger for weeks or months. With biological weapons, infections may not be contained and spread to the whole of humanity.
Just stop it. You guys are making yourselves look foolish trying to argue any basis at all for private ownership of WMDs.
A logical, moral case can be made for government not to own WMDs. Such a case may be countered by practical concerns. But a case against government ownership can be made.
No rational, moral, sensible case can be made for private ownership of WMDs. It is beyond silly. It is sad and disturbing.
Please, let it go and just stop.
Charles