If you do find a way of disabling it , insurance companies might consider it a modification from original.
It may indeed be an increase in security but good luck convincing your insurance company of this if the car is stolen.

They charge a premium based on their assessment of risk . Some folk get their premiums increased quite unfairly because maybe a Range Rover or two has been stolen in their post code area.
Disabling keys by double switching, or (as I do) use a faraday bag to prevent relay theft is a reasonable precaution. You could use a visible steering lock to deter causal thieves.
But ultimately no car is 100% safe from determined thieves. They could take the car away on a recovery truck. Or carjack it from you ,complete with yours keys etc , by violence or a distraction deception .Both are extremely unlikely .