I see your point. Maybe all 30 people in there should have stood up and done a coordinated walk out to really protest. Or they should have gotten into a direct shouting match with Kachnic or talked over her.
However, at the end of the day, most (not all) rad oncs are generally timid people who have been trained to not say no to somebody who has any control over them. We learn to 'play nice' with our referring docs, some of whom we think are idiots (at least at times). We learn to 'go along' with a treatment plan that isn't optimal or standard of care, in our opinion (or sometimes, objectively).
This carries over into academic, where the heads of the ABR are seen as those in power and thus not to be openly retaliated against for most, even for PDs, most of whom are NOT full professors.
Not saying that the response was 100% what I would have wanted at ASTRO, but I think placing our anger in the PDs (as a whole) for their response to the ABR fiasco is misplaced. Yes, there are certain PDs active on ROHub and Twitter who blame SDN for all the problems, but they are to me a vocal minority of PDs (similar to how SDN is a vocal minority of the field).