Don't Ask for the Screening Manager
I understand the initial reaction to asking for the screening manager. But, I can tell you, 90% of the time they're going to support the screener. Remember, they're only thinking, CYA.
Instead, ask for the FSD (Federal Security Director). And, trust me on this one, use the acronym, "FSD". When they hear that acronym, they know you're more than just a sheeple.
Some day I'll explain why in another post.
Ask for the FSD, and be prepared to wait until he/she arrives, because they're probably not in the sterile/screening area, they're in some office, reading the latest BS from TSA HQ. I had to wait 12 minutes before the FSD arrived at one airport. After seeing what was going on, I received an apology, his business card and went merrily on my way.
ASK FOR THE FSD!!