Ripped, too bad you obviously found the wrong type of ''behaviourist''. Unfortunately, anyone can call themselves that with no real education in the field at all. And there are some people out there that offer sham dog behaviour courses on top of their so-called training courses. There are good ones out there but they seem to be few and far between. Sounds like you picked a hack.
I too have fear-aggressive dogs. Three actually. All have responded amazingly well to counter conditioning coupled with tiny rewards of liver chips and other highly nutritious bits, subtracted from meals. One dog had been physically abused by a previous owner, had an extensive bite history and was a particularly hard case. The other two had insufficiant socialization as pups and were just fearful of new situations and other dogs. None are overweight. All three approach other dogs in a civil, polite manner now. And it hardly took any time at all.
I agree that people are not dogs, but we are both animals and both mammels, therefore have a lot in common. Of course there are some pretty major differences, brain structure and capasity, body structure etc, etc. But overall, we are similar in more ways than not. Relating to a dog as if they share some common atributes as humans has been my way to having a successful relationship with my current and past dogs. They have so much to teach us, it's a shame when we don't listen.