As someone with a nuclear background, I could provide a couple of reasons why I am not worried and am skeptical that there is a "cover up". First things first, count rate does not translate into biological hazard measured in Sv. Biological effects change with the energy of the radiation imparted and the type of radiation. If you take apart your smoke alarm at your house and put a Geiger counter to it, you will get thousands of counts in a matter of seconds. But there is no danger because the source inside emits alpha particles which bounce of your skin. The biological effects also depend on energy of the radiation, and the EPA link you provided demonstrates this. Depending in what gamma energy range the detector is set up to detect, it will register radically different count rates. As you can see they register over 1000 CPM in gamma energy range 2. So your claims of " 7k+ CPM is about 49 mSv" is just not science and doesn't mean anything.
Second, radiation is really easy to detect, even in incredibly tiny levels, which is why accidents that happen half a world away, like in Chernobyl or Fukushima, can be picked up here in the US. So the idea that any harmful event could be covered up is ridiculous. If a significant release happened in Indiana, the Turkey Creek Point plant in Miami Florida would pick up the radiation.
Third, the assertion that somehow this is a nuclear caused event. Like I stated above the CPM varies with the energy range the detector is set, so it could be that the Lower Level Discriminator (LLD) broke on those detectors. But even if it didn't, that doesn't mean the uptick in radiation is nuclear related. The nuclear plant by Crystal River in Florida gets false alarms frequently from the radiation that comes blowing over from the coal plant only a few miles away.
So to sum up, the uptick in count rate doesn't translate into everyone getting 49 mSv in the area, or "lower risk of cancer." If your conversions were true every family in America would be dead from their own household fire alarms. And radiation is really impossible to cover up, and any government effort to do so would fail quicker than it took you to put together this post.
Edit: The reason I wanted to post this is because I understand why radiation is scary to the public, it is invisible and could harm you. Coupled with no education on the matter in secondary schools, outburst like these are frequent. My peers in the nuclear world don't do enough outreach, they need to be less condescending to the public. My problem is that when people raise alarms like this they get a lot of attention, but often real risk of radiation like buildup of Radon gas inside homes gets ignored.
Edit 2: Spelling
