Thank you, MSY-MSP. I found another interesting reference the law of assault that shows what happened to me at that fateful BWI checkpoint meets the definition of unlawful penetration with force:

"Penetration is defined as "however slight". Merely putting a finger between the folds of skin over a vagina is penetration, and according to the intrinsic force standard, the act of penetration subsumes, or includes by inference, the act of force. " In my case it was an HHMD rather than a finger, but the definition fits exactly.

However, as you noted, MSY-MSP, the missing element here is consent or lack thereof. The only argument by which the TSA can possibly defend its practices as not constituting assault is the argument that passengers have consented to this degrading treatment. Implied consent is a misguided invention of the courts, and I look forward to the day when it will be rejected as a defense for abuse of passengers. Only explicit consent to the specific treatment intended, without the threat of LEO questioning and arrest for failing to comply, (though the threat of not being permitted to fly stands) should be valid.