Yeah FoMoCredit won't care. They'll sell the car w/ a blown engine for what they can and leave you on the hook for the remainder of the price between your loan amount and what they got for your car. + fees and all kinds of other BS. That would not be a very smart idea....Now I get your disclaimer at the end about how you don't condone doing something like this, but I have to add my own disclaimer:
Doing this will do nothing but rape your credit score and will likely end up costing more money in the end due to the CRAZY HIGH interest rates you'd ever likely see after a stunt like this.
Ford Credit is a division within FoMoCo, just like everything else. They could care less what everyone else is doing, they care about their department. They WILL NOT intervene on a warranty claim to save themselves from going through the hassle of a foreclosure and repossession. It's not their car, it's the owner's car. But they will take it from you if you don't make the payments. Nobody in the BANK that is Ford Credit is going to give a hoot why you didn't make your payments.
As stated above, this TSB changes nothing. To tune a car under warranty requires the understanding that you may damage something; to expect Ford to pay for it is madness. I haven't spent much time on here, but I am a mod at a Ford truck site and have yet to see someone complain about voided warranty who hadn't either neglected it or tuned it. Ford wants satisfied customers who return to buy more cars; screwing them out of warranty work is counter-productive.