Locks to me are stupid...
Does your brother subscribe to this train of thought? Was his luggage locked or unlocked?
I use locks for two reasons. One, in the hope that an opportunistic thief will go for the unlocked case before they go for mine and secondly, because the first thing I do when I pick up my case from the carousel, is to check that the lock is still intact. If the lock is missing or broken, I'm going straight to security then check if something is missing. It's an easy visual clue that someone has interfered with my luggage. Your brother was home before he realised he'd been robbed!
True story. A few years ago my friend picked a suitcase off a carousel and went home. Only once he got home did he realise that his key didn't open it. He called the ferry port and they said that a lady had his (almost identical) case and had reported hers missing, so he drove back to exchange them. Only after he'd handed it over did they tell him she had thousands of pounds worth of jewellery in her bag! So even if you don't get a petty thief, you might simply get someone accidentally taking your bag. I've also wondered in the past, how many of the bags airlines 'lose' are actually picked up deliberately. If someone checks in one bag but takes two at the other end, how many people would notice them doing it? By the time the victim realises they are case-less, the thief has gone.
All my valuables are in my hand luggage. If your brother is insulin dependent diabetic he's crazy to let his meds and glucomitor out of his sight. If he placed all his potentially life saving equipment in an unlocked suitcase... well, some people may as well walk around with 'victim' tattooed on their heads.
As for your final point about getting something 'out' would mean they could get something 'in' "like a bomb". I think it is much easier to slip someone a few dollars to 'look away' as someone leaves with a large parcel than it is to get them to look away as they arrive with it!
