So almost all the people we’d like to keep Davis’ identity secret from–the Pakistani government and the Pakistani people–already either knew or have been operating based on the assumption that he is a spy. The one exception, of course, is the Taliban or other extremists, who would no doubt like to know whom Davis was speaking to in their ranks. But to the extent they haven’t already guessed those details, the Pakistani government now must be trusted to keep them secret, if they will. There’s no more or less that the Taliban and Al Qaeda will learn about Davis based solely on US reporting confirming he is a spy.
In other words, had they revealed his CIA affiliation, American newspapers would not have revealed anything to the key people we’re supposed to be protecting Davis’ identity from; those people already knew or assumed it.