my leash reactive rescue got rushed by an off leash dog in a posted on leash park today and the owner told me my dog was the problem, i need to vent and also ask whether im wrong about how this should have gone

need to type this out before i keep replaying it in my head. Ollie is our 3.5 year old cattle dog mix, we adopted him at 2 from a rural shelter that had him listed as "no dogs" after two failed placements, and weve spent the last 18 months working with a certified behavior consultant on his leash reactivity. he is a project and we know that. we do not take him to dog parks, we do not take him to busy trails at peak hours, we do not let strangers approach him. we walk him at a small neighborhood park that is clearly posted "dogs must be on leash at all times" at every entrance, we walk him on a 6ft leash with a front clip harness, we cross the street or turn around when we see another dog in the distance, and 90% of the time this system works.

today it did not work. we were about halfway through our normal loop, Ollie was doing great, we came around a bend and there was a golden retriever off leash about 40 feet ahead of us, no visible owner. i started to turn us around and the golden spotted us and came running at a full sprint. i stepped in front of Ollie, put my body between them, yelled at the golden to stop (which of course did nothing), and the golden got close enough that Ollie lunged and grabbed him by the scruff. no puncture, the golden yelped and jumped back, i separated them, and thats when the owner came jogging up from the parking lot where he had apparently been on his phone.

the interaction with the owner is the part i cant stop replaying. he was upset, which i understand, his dog just got grabbed. but the first thing out of his mouth was "why is your dog aggressive" and when i pointed out that we were on leash in an on-leash park and his dog had rushed us he said "my dog is friendly, he just wanted to say hi, if your dog cant handle that he shouldnt be in public." i said something along the lines of "this is a leashed park, this is exactly where dogs like mine are supposed to be able to walk safely" and he said "get over yourself, my dog didnt do anything." then he leashed the golden (so he did have a leash on him, which somehow made me angrier) and walked off. we went home. i shook for about an hour. Ollie was fine, no injury, no bite, he was doing exactly what we have trained him to do which is defend himself when something charges him in his space.

what im wrestling with. one, was my read on this right, that in a posted on-leash park the loose dog rushing us was the problem and my leashed reactive dog doing a scruff grab (not a bite, no puncture) was a proportional response, or is there a version of this where i share some of the fault i should be honest with myself about. two, what should i have done differently in the moment, i think the answer is nothing because the loose dog was on us before we had time to change direction and stepping in front was the best i had, but i want to hear from people who have been in this exact scenario. three, do i report this to animal control (the park has a leash law and this was a clear violation in a park with signs everywhere, but Ollie also grabbed the other dog and i dont want to open a door where he ends up on some list), and if so what does that reporting actually accomplish. four, more broadly, how do people with reactive dogs handle the ambient hostility from the "my dog is friendly" crowd when this stuff happens, because i have been doing this for 18 months and i still am not good at defending my dog to strangers without either being too polite or losing my composure. venting welcome, advice welcome, brutal honesty welcome, i mostly just need to not be alone with this today