Recall the Liberal argument that Obamacare is the law of the land.
Shooting someone who has not threatened anyone physically or verbally is WRONG.
I agree with that (with some very narrow exceptions), but my objection was to your contention that a threat of force was not enough, that what was required to justify the use of deadly force was to be attacked (unless you want to claim that "attacked" and "threatened" are synonyms).
In our legal system, you may not physically defend yourself until attacked. Threats are not sufficient to justify a violent reaction.