It is an environmental hazard, but that is not EPA jurisdiction to dispose of. The NRC exists specifically for things like this, in fact its predecessor the AEC was split into two departments, the ERDA for research and the like, and the NRC for safety concerns. With expressed protections for whistleblowers working on nuclear projects they have concerns over. Even if it was EPA territory, he brought a cop and a worker and just shut it down, which is not disposal by any stretch of the imagination