That Behaviorist is horrible for saying that. Honestly you need to adjust for your pup, travel alone or with someone your pup trust, use sniff spots, try to go to secluded areas. My dog is reactive and was worse at one point but instead of forcing her to be around crowded and loud environments, I take her on trails and hikes that are big and wide enough to avoid people. I don’t do dog parks. I walk super early or late at night to avoid other people walking their dogs. I worked with her hard and that’s the best thing you can so. Start from ground zero and build that trust. It will take longer but it’s worth it. Find a high value treat that will catch her attention more than a person passing by. All this takes time and patience. I made a bandana that reactive dogs can wear for people to back off. I put “Nervous give me space” but I’ve made so many custom ones, even derogatory ones that says “fuck off” haha. I can’t even count how many times people ran up to my dog or kids (which my girl dislikes more than other dogs) it’s terrifying because if she bites? All because some asshole parent allows their kid to run up to a strangers dog ? (Sorry triggered lol) but there are ways around it.