Manning and Snowden disclose info that makes the US look bad, so: "EVIL COWARDLY TRAITORS"
Petraeus and Cartwright disclose info that makes the US look good, so: "Meh, mistakes made, water under the bridge now. They're all patriots."
The mythology associated with leakers/whistleblowers is astounding, as TFA notes. Even when it's proven otherwise, the noise machine (aaah! FAKE NEWS!) gives it a sense of realism and unassailable truth.
1) Police have guns. Republicans instinctively protect *anything* to do with guns.
(you could stop right there, but...)
2) Police represent law and order. The incoming president says he's the L&O president, so they want to stay on his good side, by any means necessary - to include cowering. Cops have pretty big unions, too ... and unions of (preferably uniformed) gun-wielding people are attractive parts of the Republican constituency and must be pandered to.
(you could stop right here too, but...)
3) Republicans have nothing better to do that 'work' on wedge issues and/or naming post offices since over the past decade or more in Washington they've proven an inability to govern collaboratively, generate new ideas, or govern generally.