Yes. But we are not hearing of a plea deal at this point are we, so it would seem Durham has not yet gotten him to implicate anyone above him. If he had, we might be hearing of a plea deal today instead of a mere filing of charges.
Um, he's pleading guilty to a felony. This would appear to mean that they've gotten what they want out of him and they're allowing him to plead to a single charge in return for his cooperation. I suspect they will delay sentencing until he actually testifies, if needed, in any upcoming trials of those above him.