The ten years deal came about after his conviction, they don't mention in this article what plea bargains he was offered before the conviction:
Leading up to Mr. Williams’s trial, federal prosecutors offered him various plea bargains, but he turned them all down. He believed, quixotically enough, that he deserved his day in court. He held this conviction even though prosecutors precluded him from presenting his compliance with state law as a defense to the federal charges. Without this essential context, the jury heard a deeply distorted version of Mr. Williams’s story.
After Mr. Williams’s conviction, the United States attorney general’s office came back with a new deal. If he waived his right to appeal, they would drop most of the charges so that he would face a minimum of 10 years in prison and pay a $288,000 judgment.
you have to read opinion pieces in the nytimes very carefully because they are good at forcing you to agree with them.