I live in the subdivision.
When you purchase a home there you are legally required to be provided and then sign a document that outlines the history of the Rocky Flats plutonium facility. I was provided this document and had to sign it as do every other homeowner here.
What I've learned is that people who don't really know anyone that lives there or have never bothered to talk to anyone who purchased homes make assumptions about the entire area. They assume that the people that purchase homes were ignorant rubes who weren't aware of the sites history. I knew about the site and researched it for well over a year before I chose to buy a home in the neighborhood.
I spoke with a nuclear physicist who lives in the neighborhood. I also have a co-worker who is also a physicist and was once in charge of a nuclear reactor at his university.
There were over a quarter million soil samples taken from the area surrounding the core containment area. There was decades of testing by the EPA. It was a super fund site for decades.
Additionally the neighborhood is not built on the site. It is built outside of a perimeter, well over a mile and a half from the core area that was covered over with concrete where the soil still contains traces of plutonium.
As you pointed out plutonium is indeed in alpha emitter rather than gamma. It's also extremely heavy and oxidizes on contact with oxygen. It's not the kind of substance that's going to blow around. It will kill you if you inhale it or ingest it of course.
I have many photos of herds of elk in the refuge that surrounds the core site. It's not at all the wasteland that people make it out to be.
Additionally your first statement claiming that a single company sues people who want to do testing is completely incorrect and can't be backed up by any references. I live here and I happen to know that no single company developed the subdivision. It was purposefully set up by the government of Arvada as a zone and split amongst multiple developers. Additionally more testing has been done in the land around the refuge which the developers have no control over or legal standing. As to testing within the subdivision, the homeowners can test whatever they want in their yards with no permission from the developers. Like a lot of anti-nuclear misinformation it doesn't even make sense when you dig into it.
Additionally the fire never got to a point where it was going to hit Rocky flats. Rocky flats and the surrounding area were placed under a pre-evacuation order in the event that the wind shifted. I live here that's why I know this.