Rhodesian Ridgeback is your answer. Very good guard dogs, aloof with strangers, very protective of their owners and very well tempered.
But still need a LOT of attention and exercise.
But the real question is, why should he get a 'potentially' dangerous dog, when there are a huge amount of other options?
1/. Every dog is 'potentially' dangerous. His other options are down the route of alarms, shotguns and electrified fences.
2/. Yes, there are hundreds of other breeds that are not officially listed as 'potentially dangerous'... Labradors, well known for their family-friendly qualities and calm suitability as Guide Dogs, are also very high on the Bite List...
3/. All three of my dogs are breeds of bad temperament... under the wrong circumstances.
If someone offered you two glasses of water and said one had a poison in it which had 50% chance of killing you, would you choose that glass?
If someone told you you're twice as likely to die from a wasp sting than being bitten by a dog, would you still go outside?
Or if you were 35 times more likely to choke on a hot dog, would you ever eat one again?
No, you'd choose the glass with nothing in it. Why take the risk?
So you're advocating what... a toothless, legless dog for the OP?
A dog with all its dangerous bits removed?
A cat, perhaps?
Maybe one of those Guard Chinchillas?
He already has two dogs which I'd wager is enough to put off 99% of any potential burglars regardless of what breed they are.
You put the tinny, yappy "arf arf" barks of his little dogs up against the beefy, booming, deep-chested "RROOOOOOWFFF!!" of my Lab and see which one scares a burglar more....
Therefore the reason for getting a 'dangerous' dog is flawed.
"We will never live in a world without dog bites or risks, nor will we ever live in a world without irresponsible people. We can, though, live in a world where dogs are judged as individuals and by their actions rather than their appearance, and owners are held accountable for the actions of their dogs".
The best you can hope for is a dog that barks enthusiastically and then greets your burglar with a wagging tail.
That's pretty much all a Guard Dog would do - It guards, it doesn't attack.
Well... technically, a 'Guard' dog would intercept the stranger and drive them off or restrain them, but this can result in more conflict and your dog could get hurt.
Ideally you want a Watch Dog, that purely alerts you to intruders and does not stop barking until you tell it to.
Either way, both types would likely be family-friendly and, properly trained, would only kick off on those it does not recognise.
Yup and of those not banned by the act how many are staffies, bull terriers etc..
How many only look like those, but are instead purposely crossbred to make them dangerous?