[monkeymeister]

Likely to avoid defeat attempts. The corporate email requirement acts as a first-line defense to at least try to stave-off would be skimmers / scammers grabbing the CAD file and working out the measurements needed to defeat it.

[Operyl]

Seems easier to just pay off an underpaid Target employee.

[kalupa]

ah, nothing like security through obscurity!

[pbjtime]

Which should not be your entire strategy but is completely valid layer of mitigation