In other words, you know it's wrong, but want to pretend that it isn't. Why do you think that obvious safety rules don't apply to you? It is impossible to completely empty any fuel canister of residual fuel. It is completely irresponsible to even think about taking a gas canister on an aircraft, and thus potentially endanger hundreds of lives. Gas canisters and camping stoves are cheap enough to buy new. If you can afford to fly from SFO to NZ, then you can afford to buy new gear.