chollie

You could try to arrange for a TSA Cares specialist to meet you at the airport and accompany you through the screening process. If the specialist agrees to meet you and actually shows up, that should prevent outrageous abuses but there should not be an issue with you sitting down while they process your shoes.

You could also consider arranging for wheelchair transport to the gate. It's more than you need, but you're unlikely to get hassled about sitting down while your shoes and feet are processed.

I wouldn't worry about the bloody sock. I've got a friend who got toenail fungus - it's pretty awful to look at. They swipe their gloved hands over his nasty toenails and don't even blink (or change their gloves before handling the next pax, unfortunately).