Would it be possible to add a setting to prevent players from pushing a vehicle when there's a locked code lock on it?

There's already a config option for this.
"AllowPushWhileLockedOut": false

Ok, I didn't realize that was there so I checked and I have that option set to false and players can still push locked vehicles.

Which vehicles are you seeing this with? Wondering if it's affecting all vs specific vehicles.

I will need to double check this, but it's with the standard cars in rust. 

Ok, there was an issue caused by the December Rust update which caused the plugin to no longer work for Modular Cars. After fixing and releasing an update to the plugin last month, I did not specifically test the push feature, so maybe that feature has been broken for Modular Cars since December. I will try to reproduce at my next available opportunity.

Merged post

I just tested and I was not able to reproduce the issue. After setting "AllowPushWhileLockedOut": false and reloading the plugin, I was not able to push Modular Cars without first authorizing on the attached code lock.

Please make sure you are running the latest version of the plugin, that you do not have authorization to the car's code lock, and that you do not have the master key permission.