Just a quick bit of background to what we're discussing here:
Proving a source is "biased" is not an argument. It establishes literally nothing. Everyone is biased in some sense. Biased sources can be absolutely accurate. Unbiased sources can be totally wrong. "Bias" is not a determinitive factor of anything.
Proving that a source is "unreliable" is a slightly better argument, but still not really a good one. You may be able to cast doubt on what a source is saying by proving that they often say things that can't be trusted. But so what? We're not discussing the reliability of the source in general. We're discussing ONE article written by a source. This is the equivalent of a Irish person announcing, "I'm Jewish," and you responding, "Nope. I don't believe you. Most Irish people are Christian. Therefore you're Christian."
The best way to refute a statement is to ignore who the source is, and focus on what they're saying. This is hard. It's time-consuming. It takes work. It is also beyond Royce's mental capabilities and emotional intelligence level, so he prefers to dash off a hasty, "Haha, your source is unreliable!" rather than actually saying something of substance, then pat himself on the back for being so brilliant. (As the icing on the cake, I should also point out that he doesn't even do that very successfully, since merely announcing something, without any type of documentation, proof, or evidence, is hardly a successful refutation of a source's credibility.)