I'm sure his lawyer will want to argue all that now, but my advice to you is to read the transcript of the recording from the other story about it. He was bragging about his past success in bold, unambiguous terms, in the context of promising to help somebody pass.
And the technique isn't about filling out forms, you put a tack in your shoe and use it to throw off the baseline measurements. You also do certain core exercises during those baselines, when you're supposed to be sitting still and relaxing. When you get into the details, it is neither innocent nor passive.
It is also not a technique for avoiding false positives, because if it does do that it achieves it by creating false negatives; negatives that are false, even if the answer the person gave is true. (that's because polygraphs aren't "lie detectors," and a "false positive" isn't a falsely detected lie, but accurately detected discomfort that is for an innocent reason) Having manipulated the test is a real deception, there is no way to attempt to mask a presumed test error (that hasn't even happened yet) with a deception that better matches what a person expects the result to be, and then say that was innocent, it was somehow corrective or preventative.
To follow your metaphor, it is like offering to help people avoid audits by fraudulently altering all the paperwork to remove any obvious red flags. If you actually come right out and say that that is your service, then you are indeed an accomplice.
If a mobster comes into your laundry service with a dripping red bag of laundry, and you just want the cleaning fee, don't ask questions just clean the laundry. If you didn't know, you weren't an accomplice. You're just the dry cleaner in the same neighborhood as the killers. It was probably brake just fluid, you figured.