It's at the discretion of the DoJ. Could very well be a cooperating witness. Prosecution would be deferred under a plea agreement unless there's blanket immunity agreement, which is definitely possible and probable. This would fit with the current strategy of pyramid prosecution. Immunize low level ones to get the big fish.
Implying Mueller is the bullfighter, and will "kill" the "bull" (Trump) when he's done.
PETA response would be "Oh uh well uhhhhhhh….this is different because it's Trump." These people have invented the "Trump Exception" to everything. Common decency, perjury, blatant hypocrisy, whatever.
Yes plea deal would be "You get this if you give us that. And if you don't give us that, then this deal is null and void." It's not declined prosecution but deferred prosecution. Depends if the subject holds up their end of the bargain. Blanket immunity agreement in exchange for any and all testimony (like what Hillary's lackeys got) would be considered declined prosecution for legal purposes. The immunity is the same as deciding to not charge at all.
Technically, OIG shouldn't have even made this referral because it's for a civilian but some technicality probably allowed him to make the referral. DoJ could still ding the fucker, no one is outside the jurisdiction of the DoJ.
OIG doesn't prosecute anyone. Has no prosecutorial power whatsoever. Only power to make criminal referrals. OIG made one here, don't know why he was able to refer a civilian. Or if that's the technicality that made the USA decide to not prosecute. Or the SA is cooperating.
Rats on a sinking ship. McCabe is contradicting Comey with his testimony, so question is who's lying? Both of them, probably. Not the big stuff but bullshitting about the details.
I agree with your post. To restate, DoJ may very well have declined prosecution because Horowitz did not have the authority to make the referral in the first place. That or there's a lot of singing going on and the US Attorney declined to prosecute due to the SA being a cooperating witness.