Instead I put an easily breakable cable tie on the zips as a tamper evident seal. The one time I've had a bag come back with it missing has been the time the TSA decided to inspect my bags.
vs a lock, which somebody can open and re-lock and I'd be none the wiser.
The tsa checks my snowboard bag every trip, both directions. Sucks for them, as it's full to the gills of sweaty sopping wet gear on the way home and I usually have to have someone sit on it to get it to zip up.
As a joke I would put those notes they leave when they inspect your bag in there. I was up to 22 of them when one stickler agent throw them all away except the new one. I was sad. It was fun to imagine them opening that bag every time I flew.
It is really easy to open a cable tie unharmed, and lock it again with that same tie. Just push the "lock" down with a sharp object.
Besides that the TSA has cable ties too. It's not like you can't buy them off the shelve. In your example case the TSA clearly didn't bother spending the time to make it not look like they opened your bag, but it isn't a very reliable way to see if they opened your bag.
Make sure to fix the zippers in place. Otherwise it is very easy to still open the bag by just prying open the zippers and closing them again by moving the tied-together zippers.
Instead I put an easily breakable cable tie on the zips as a tamper evident seal. The one time I've had a bag come back with it missing has been the time the TSA decided to inspect my bags.
vs a lock, which somebody can open and re-lock and I'd be none the wiser.