Most mini lock boxes like this have a cable to loop around something like the seat rails, and still had enough slack to get into your lap for emergency use.
There are plenty of good and convenience tools out there to defeat this. I keep this in my off-road bag and its amazing what it can go though. Knipex mini bolt cutters. I can go though a chain link fence like butter.
I would consider most any of these solutions for temporary / short term storage at best. If someone really wants it, they are going to get it.