He is already profiting from the US prison system. Also I would not recommend tangling with prison guard unions for his first project, tackle something unrelated and revisit it when more experienced.
There are many opportunities outside of prison guard unions for innovation regarding the overall institution/process of incarceration in America.
Domain expertise will only be built by tackling a problem in that domain. How could one possibly decide against pursuing a topic without trying it at all?
Tough, seemingly entrenched markets often prove to be the most interesting: SpaceX, Uber etc