I think there is a pretty big line on the spectrum of "lying and fabricating," from reading/erasing a name on a report and lying about it to maintain anonymity (not morally blameworthy to an extent that the person shouldn't be protected, I don't think) and totally making up events to cast someone in a false light (very morally blameworthy). I don't think you can draw a bright line rule like "[j]ournalists should not protect their sources if they lie or fabricate information" because of this spectrum.