Hedwig, you know I've been pulling for a successful outcome to you and Bruno's issues here but it looks to me like you're looking to validate your reasons for doing what I think you'll ultimately do - turn him over to a shelter or have him PTS.
Frankly I think you should give it your best shot with him. For just a while, stop considering rehoming as an option. Don't work with him like it's temporary, work with him like you're going to have to live with this dog for 10 years or more. You'll notice a change in your approach.
If you want a little bit of advice... You need to get OFF the "dominance" theory and the "be the pack leader" crap NOW. This is bullying, plain and simple. It's not helping this dog, just making him feel more tense around strangers. If I were you I'd work on some desensitization, not flooding. Don't force him to suppress his reactions to strangers, that'll just make problems worse. You want him to stop reacting because he's no longer afraid, not because he's afraid of being punished for it.
Look for some books, if you can - Click to Calm by Emma Parsons; Control Unleashed by Leslie McDevitt; The Other End of the Leash by Patricia McConnell... Any of Karen Pryor's clicker training books, Culture Clash by Jean Donaldson... Just read up on how to effectively communicate with a dog without the faulty dominance theory interfering with your thinking.
I really do think you can help Bruno and at the very least make him adoptable. If you don't feel you are able to do this, then personally I would spare him a life of fear and humanely let him go.
Frankly I think you should give it your best shot with him. For just a while, stop considering rehoming as an option. Don't work with him like it's temporary, work with him like you're going to have to live with this dog for 10 years or more. You'll notice a change in your approach.
If you want a little bit of advice... You need to get OFF the "dominance" theory and the "be the pack leader" crap NOW. This is bullying, plain and simple. It's not helping this dog, just making him feel more tense around strangers. If I were you I'd work on some desensitization, not flooding. Don't force him to suppress his reactions to strangers, that'll just make problems worse. You want him to stop reacting because he's no longer afraid, not because he's afraid of being punished for it.
Look for some books, if you can - Click to Calm by Emma Parsons; Control Unleashed by Leslie McDevitt; The Other End of the Leash by Patricia McConnell... Any of Karen Pryor's clicker training books, Culture Clash by Jean Donaldson... Just read up on how to effectively communicate with a dog without the faulty dominance theory interfering with your thinking.
I really do think you can help Bruno and at the very least make him adoptable. If you don't feel you are able to do this, then personally I would spare him a life of fear and humanely let him go.