I believe that the nudeoscope will flag an adult diaper as an anomaly, given that women have reported that sanitary napkins have registered as anomalies. I think your fears are well-founded and that you may well have a terrible experience at the hands of the TSA if you go through a body scanner.
I recommend that you try everything in your power to do a self-directed opt-out and get yourself into a walk through metal detector line. You might be able to do this by choosing your checkpoint carefully and then switching terminals past security: check tsastatus.net for details. You might also be able to self-select a walk-through metal detector line instead of the scanner line at some checkpoints. If all else fails, tell the person manning the scanner that you can't lift your arm above your head because of an injury. Some flyers report that medical involuntary opt-outs go through a metal detector (but this response doesn't seem to be consistent).
Despite our most careful efforts, any traveller at any checkpoint could be chosen for a patdown for any reason or no reason at all. I completely concur with your revulsion at the thought of being touched and pawed at by these blueshirts. I was sexually assaulted at the BWI checkpoint and I will never, ever let a screener touch me again. If a TSA screener tells you that you need a patdown, the only way to avoid it is to be willing to leave the airport and walk away from your flight. They will fight you on this, but stand firm. Say, no, I will not consent to a patdown, I no longer wish to fly, I want to leave the airport now. I've only had to set this plan into motion once, but I walked away without letting those people degrade me.