Eh, the place that built the subdivision sues the crap out of anyone that tries to get more testing done. And there's a lot of methodological issues with the tests that they do have. Like using gamma radiation tests for plutonium contamination (plutonium is primarily an alpha emitter as it decays).

Also the fuckers had the audacity to name the subdivision 'Candelas'. For those following along at home, Rocky Flats was a plutonium warhead manufacturing facility raided by the feds back in the day for doing crazy stuff like lighting plutonium on fire, and not coming anywhere near close to what would be expected for storing contaminated materials. It then became one of the first super fund sites.

I think the issue is how well remediated it’s actually is. I presume that there are a reasonable number of people who doubt that the remediation was actually complete enough to be safe against wild fires

The remediations are massive concrete structures covering large swaths of the ground. A brush fire being pushed by heavy winds isn't going to do anything to it.

Additionally the large subdivision was not built on the site but surrounding the perimeter to the site. The core site is off limits to anyone as a precaution to prevent anyone from tampering with the remediations or deliberately vandalizing them.

Surrounding the core site is a wildlife refuge that is fairly large. On the outside of this refuge is the subdivision.