Nothing would prevent it from being stolen. You have some options. You can pull the ECM fuse, which will keep the computer from working and thus the car from starting, but the computer will lose its stored driving adaptation memory and it might not run well for a while after that (while it re-learns things about the driving style, environment, engine condition, etc.)
If it’s not the same as the ECM, a better option would be the fuel pump fuse.
Another option is to pull the coil wire from under the hood. That connects the coil to the distributor and will keep the car from running.