I would do a vet check and blood panel merely for my own peace of mind ..check thyroid, tick borne illnesses..and if it came back ok which I strongly suspect it would I would probably euthanize this dog. I normally would not say that based on a thread of text, but it sounds like you have already been steered in that direction by accredited trainers and behaviorists who are concerned about safety. That t me is a huge flag. And you have a son? That is deal break stuff for me.
You can't rehome him. You will never truly know what his future holds. He may hurt someone while under control of someone who "thinks" they can control him. They may hurt Silas. There are so many bad things that can happen with a dog like this. Unless I personally knew a well known K9 person who would take him on, I would not be offereing this dog out for rehoming.
I am so sorry. I have had to do this twice in my life, once due to mystery change in behavior (could have been medical or genetic). Spent a TON of money on vet tests and top notch trainers. The other dog was pure genetics. Very unstable dog that was always waiting for death to come knocking, from puppyhood, from day one, like what you are describing. He reacted to being startled by biting. Everyone who knew him (and I hang out with trainers) supported the decision. Shame but he needed to be released from his demons. Seclusion is no life for a dog, and like a previous poster said he was a dog that would keep an owner hostage should they choose management.
Please stay FAR away from craigslist or FB listings. Honestly if the breeder said to euth..I mean..I know you said the breeder did nothing wrong, but I seriously hope the breeder seriously reconsiders this dog's pairing of lines that were used as not suitable for future breeding.
Again. very sorry. Been where you are.
Frankly I think it is way more humane to this poor dog in the grand scheme of things to bring him home some hamburgers, fill em up with tranquilizers and let the last thing he knows be his person feeding him hamburgers