I really don't have an opinion one way or another, but it is always a red flag to me when a fighter says, "I have never knowingly done X".
I have been around many athletes who just take what their trainers give them without asking questions. This gives them plausible deniability that they never knowingly took X.
Why the caveat? Most people would just say flat out, "I never took X". It's a carefully worded denial.
For example, Lance Armstrong saying that he never took any BANNED PED's. It means that he was taking PED's that just hadn't been officially banned yet.
Take it with a grain of salt from some random guy on the internet who was trained in interview/interrogation techniques with over 25 years on the job.
"God gave you a brain, and it annoys Him greatly when you choose not to use it."