That's a different story from 2014, not about the 2005 broadcast.

Why doesn’t radio free asia let us verify their claims with the evidence they must have gathered to make the report? Y’know, like a reputable news agency would?

You might as well ask why journalists don't put targets on the backs of their anonymous sources by publicly identifying them. ALL reputable outlets sometimes use anonymous sources to protect the lives of people living in precarious situations. North Korea is not exactly known for treating citizens who talk negatively about how the government operates there well.