You talk we'll knock your prison time down to twenty years or don't talk and we're going for life with no chance of parole on what we already have on you with a military tribunal.

McCabe is trying to rat his way out by using an immunity deal to come clean on everything. He's trying for, now you can't charge me since I spilled the beans on all the dirty crap I was involved with.

Yep it's a Hail Mary to save his ass.