Strange that the person wasn't arrested. Is there any way to findout the persons name in order to determine if it's a set-up?
Given that aviation events automatically come under the terrorism act and therefore suspects can be arrested and held without charge good chance this is some sort of a setup or old mate works for ASIO.
If you could work out the chances of:
Someone taking a gun onboard
ANYTHING falling out of a carry-on bag
That anything being a gun
The bag having been on top
The hostie seeing it
What are the chances of the regular joe public having a taser in the first instance? How would you even go about getting one?