The TSA locks just slow down the baggage handlers from going thru your stuff and on overseas flights you’ll find that other countries security won’t have keys to the TSA locks either.
Once while TSA was inspecting my gear the purge button on my 2nd probably got caught on the mesh, popped off and landed outside the bag. That’s why in the pictures of me in the Galapagos I’m wearing a loaner 2nd.
Greg, If you are willing to pay the airline fees you can take a tank but it needs to be empty, valve off and neck opening taped to keep bugs out. I was once called to baggage check to breathe out of my pony to prove it wasn’t an explosive gas, speaking like you just breathed helium didn’t go over well :(