Kind of misses the whole point! This story pretty much spoiled the party of WSJ‘s entire SafeHouse announcement. In fact, the lack of protection for SafeHouse sources in many ways became a bigger story than SafeHouse. So in response, the WSJ has already issued a clarifying statement, which says this about anonymity:
Not entirely comforting. While saying that nothing is more sacred that sources is undoubtedly a fine gesture on WSJ‘s behalf, it’s not quite the same thing as actual contractual language.