Yes, in essence we are both correct. There was never an operation called Gunwalker but David and Mike coined that name to give the scandal itself a name. Gunrunner was and is a name of an agency-wide operation that has been in effect since the Bush administration. It's purpose is ostensibly to interdict illegal gun trafficking. It is the operation that receives funding by name. Operations like Fast and Furious and Castaway are local ATF division operations that get their funding from the over-arching program called Gunrunner.
So "walking" and "gun walking" are verbs (adjectives?) that agents themselves use to describe allowing guns to disappear into the criminal netherworld. "Gunwalker" is a noun used by the press (and coined by Dave and Mike) to describe the scandal.