I was refuting your assertion that somehow the fourth rule (actually the first) made the situation of firearms handling less safe. In the severely constrained model of the real world you posit, wherein everyone obeys all the rules all the time, I claim that the end result would be the same. Ergo, the four rules are not less safe than some proper subsets of the four consisting of three
Outside of that hypothetical and very limited microcosm, in the many and varied real world situations, the four rules would be superior to any version of three I've yet seen
You weren't refuting me at all, you were responding to someone else. I simply noted that you were attempting to prove argument #1 - unnecessary and unhelpful (and doing a fine job, I might add).
Any harm from the fourth rule is clearly argument #2, which I also pointed out and didn't try to further in our discussion. I was just happy you were helping to prove #1.
If they wind up the same, neither set being less safe as followed, you supported 3 being sufficient but not better than 4. That's enough. Thanks.