Johnson never made ANY statements in court. In fact he refused to testify. Part of his agreement when becoming an informant was that he'd NEVER be made to testify. He also never wore a wire. He never wanted to fully be a rat.

When they were locked up together, Gotti told Willie Boy in the MDC after Willie Boy's status as an informant was revealed that he'd be given a pass if he didn't testify, because at the time it seemed he gave minimal info. That he'd be cut off from the Family totally, and couldn't hang around the Family, but that he'd be spared.

A few weeks before he was killed, Gotti got some case related info which detailed just how much he had ratted over his decades as an informant. That pushed him to expedite Willie Boy's murder, along with the fact that Willie Boy working in the drug trade on his own (on Family turf).