Modern cars are not very secure. Many of them can be hacked and started in seconds via the OBD2 port using a laptop. This is a big problem on the fast Fords (ST/RS models). On my Fiesta ST I moved the port and put a fake one in it's place to prevent it.
I think if you want to make this one more secure, make the start button removable. It's actually quite easy to remove as is