I never said it "would have saved all those kids". I said there would have been "fewer dead kids, possibly even no dead kids"
No indication either approaches anything near reality, so it's sort of a moot point which one you meant. If you meant "it's within the realm of possibility that having armed teachers may or may not have lead to fewer death or injuries" that's pretty accurate. What you've actually stated is unprovable, untestable, unfalsifiable and useless. May as well have said "if more angles had been flying over the school that day, they would have caused that wicked gunman to accidentally shoot himself, saving countless lives"
What about, and I know this is wild, but say the school had made a trap where a lot of spaghetti fell on the shooter and knocked him out? That would have completely eliminated the threat.