Not really. Illness is a proximally transitive property; being in the same room as an ill person can, indeed, make you ill. It only leads to support of silly inference patterns if you disregard the actual meaning of the words used in the logical statement.
Consider the actual meaning of "therefore" used in IlyaShpitser's post. It's logically stronger than "and".
In the least convenient possible world where health care is good and diseases aren't transmissible, the naive causal inference would lead to the same conclusion.
My roommate recently sent me a review article that LW might find interesting:
Personal observation says that LWers tend not to drink very much or often. Perhaps that should change, to the degree suggested by the article?
Full article here.