It doesn't do anything of the sort and there is nothing new in the Schneier article. Why would your average non-IT journo understand about PGP? If the journo was told it was a temporary password then they are very unlikely to say, "oh no you are wrong you IT people, I know about stuff and this can't be temporary". I've been reading Slashdot for well over a decade and if someone I thought knew what they were talking about told me they had stuff encrypted with a temporary key, I would believe them (although I'd be wondering just how it was done).
The other angle is that why would the Guardian publish the key if they new it would unlock everything for everyone? It isn't in their interest (selling newspapers), plus there are plenty of reports of other media outlets being offered the data more than a year ago, so it has hardly just got out there.
I think the real story is it is all a screw up, journo knows nothing about IT, is bullsh*tted by Assange and believes what they are told. Assange isn't doing the security by the Wikileaks protocol, everything goes to crap.