>These and other methods are good reason to believe that AI can never be 100% contained, which gives me pause.
Easy, throw out the computer. Go analog if your work is so sensitive. Now you might say, "but what about the computers and all we use them for," but really reflect deeply over what exactly we are doing with these computers. I'll send an email to someone, no different than what I might have mailed them in years past. I'll pull up the calculator and do some math that I could have done by hand. I might write a function to ingest some data from one file and put it in another file in another format, work that used to be done with printed data and by hand.
The sobering thing with computers is that they really didn't change the world that much. We basically shoehorned them into the existing analog apparatus that controlls the world. Aside from the people who had jobs wrangling data among spreadsheets by hand, point to any company and its basically structurally exactly the same pre computers as it is today with three year leases to computers to all staff (aside from the existence of an IT department managing that gear I guess).