So best to just avoid cars with it.
Exactly. OP doesn’t say, but why own a car with auto engine shutoff if you then want to permanently disable it? That’s like buying a compact sedan and asking how to tow a huge trailer. Can’t be done.
The answer to your question is “sell the car and buy one without the feature”. It should be at least another 10 years before we start having serious issues with finding cars that don’t have this. For the record, I’m a big proponent.