They “can” take them seriously, Jim, because of the media’s own agenda. It’s a convenient (if informal) “stamp of approval” when an official inauthentically claims to represent Catholic teaching when advocating for certain political issues. The media rationalizes to itself and its viewers the same thing that some other CAF members do: that “because” the official is a baptized Catholic, “therefore” he or she represents the faith accurately and legitimately.
More than half of baptized adult Catholics do not know their faith. I am not referring to obscure facts, but to some of the most basic tenets (dogma and doctrine), in all areas of theology: sacraments, systematics, scripture, spirituality, etc. You can take it to the bank that MSNBC, CNN, and the NYT do not know the Catholic faith. And I know that because of the kinds of amazing statements from the mouths of Chris Matthews and Joan Walsh (two baptized, practicing Catholics) on MSNBC.
And in the media’s modern (shallow) understanding, if you’re a member of something, that makes you an expert. Everyone’s an “expert,” you see.