I don't interpret "fair warning" as meaning "this person is a wrongthinker, stay away!" I interpret it as "you may find this article interesting, but be aware that its source is outside the mainstream and maybe even outside the Overton window."

I guess we just have a difference in interpretations of the term. My recent (admittedly amateur) interest in behavioral economics and persuasion leads me to believe that even sophisticated people are susceptible to the effects of framing. If you prime someone to read something with a bias towards skepticism, they will either avoid it due to confirmation bias, or potentially read it differently than they would have without the prime. That may not even be your intent, but in reality it happens. And as for "outside the mainstream" - whose mainstream or Overton window? My "mainstream" actually takes Mises very seriously. It sounds like yours does not. I suppose under a broad definition, a warning could be warranted for nearly every article depending on the audience.

I read that as simply a warning about potential bias. If anything, I find that being on the lookout for potential bias actually helps be come to my own conclusions.

Very possible. But a warning about potential bias may induce an (un?)intended bias of its own!

Hearing the perspectives of all sides is only useful when they're honest. Any article which talks about Nixon's effects on healthcare and laws passed in 1972 and 1974 but skips right over the Health Maintenance Organization Act of 1973 is not being honest.

The article never claimed to provide an exhaustive list of all healthcare related laws and their affects. In exactly what way does omitting that law weaken their argument?

I don't expect an exhaustive list, but saying that Nixon's laws in 72 and 74 made our current state of healthcare while ignoring the 73 law is a glaring omission. Considering it allowed the rise of for-profit HMOs I would expect a decent article to at least address/dismiss the concern that maybe this law is part of the reason our prices have gone up so much.