[aamar]

I agree that correlation studies can be valuable, but I see many correlation studies as (intentionally or not) exploiting a propensity (arguably a bug) in human reasoning that conflates it with causation. In this situation, we have thorough documentation of multiple people clearly making the error.

I'm actually not sure the study authors should be blamed.

But: given how politicized this question is, they could have reasonably anticipated the misuse of their results, and thus could have written their results in such a way as to avoid this. Or they could have publicly corrected non-experts who cited them for causation. Or: they could have controlled for factors that would make mortality and insurance-status independent. This last option is difficult & requires complex judgement calls (see [1] for a reasonable attempt), but even if you feel the other two aren't required of academics, this last one very much may be.

(Separately, I agree that Politifact should not be trusted automatically, but these seem like reasonable analyses, and I did not quickly find anything better.)

[1] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2739025/