Your best bet is to try to mentally prepare yourself to turn it around on them as best you can. I'm not talking about their Newspeak BS about "rape victims should train themselves to think of it as security," but rather I'm saying to plot out how to make the groper feel as dirty and uncomfortable and sub-human as possible.

Since they're up in arms about anything they perceive to be threats, try sticking to questions. Ask the obvious, point out the elephant in the room. "Do you get off on this?" "So do you enjoy stroking the vaginas of strangers all day?" "Do I do it for you?" "How much do they pay you to be a Nazi rapist?" (I'd only go for that last one if they really piss you off or if you're prepared for more of a confrontation)

Keep to things that can never be even remotely interpreted as threats, but that shine the spotlight directly on what the TSO troglodyte is doing. Use your discretion - if they keep the patdown to just a patdown and don't get "personal," leave it be, but if you think they're getting too intimate, aim to abuse and depress. Maybe once there's a rash of TSO suicides stemming from traveler-induced depression and self-loathing the TSA will be forced to reconsider its actions.

People will likely say that what I advocate is cruel and unnecessary, and that's a valid opinion - perhaps a true one. But I'm drawing perilously close to saying that if they tell us we sign away our rights when we buy a plane ticket, then they sign away their humanity (and thus their entitlement to human kindness, dignity, compassion, and fair treatment) when they take a job with the TSA. That a TSO is no longer a "her" or a "him" or a "he" or a "she," but simply an "it," a soulless, mindless conglomeration of carbon molecules that happens to look and sound and try to act human, but is a foul mockery of all that human beings stand for.