A journalist who violates conditions of 'off-the-record' is not going to be a journalist for much longer, because nobody will tell him anything. The 'bastards' who made the rules, in this case, are the journalists themselves.

I'd guess that the gain for Mr. Rusbridger is that he retains his privilege to be able to quote from similarly absurd conversations with government officials in the future.

That rule is actually made by journalists, not governments.