This first version of the camouflage watch would be the best for your nephew's line of work and the least conspicuous compared to the second version that has a positive dial compared to the first version's negative dial and a silver chrome G light button compared to the first version's matte black G light button.
First version - GDX6900CM-8 (more subtle)
Second version - GDX6900TC-8 (slightly more blingy)
As for the alarm inadvertently going off, you can let your nephew (or anyone else who is reading) that they have to make sure the "SNZ" (snooze), "ALM" (alarm) and "SIG" (hourly signal) notifications are not marked.
SNZ: sounds the alarm for 10 sec, then stops on its own. Emits the alarm again in 5 minutes. The only way to turn it completely off (rather than shutting the alarm off by pressing a button for the watch to go off again the next 5 minutes) is to go into ALM settings and deactivate the SNZ marking. You can also choose the month and day the SNZ alarm emits as well.
ALM: choose a time and it will go off daily. AL1 and AL2 are the two different alarm times you can set.
SIG: emits a beep at every hour.
For more information and full setting explanation (not the same model, but the way to perform settings are identical to the camouflage model), click here: http://casiowatchparts.com/how-to/adjust-alarm-on-g-shock-g-7900/.
ALM marking activated (make sure nothing is marked so beeps and alarms will not inadvertently emit on its own) - AL1
ALM deactivated (as shown by no marking) - AL1
ALM deactivated (as shown by no marking) - AL2
SNZ deactivated (you know by now)
SIG deactivated (ditto)
Once the SNZ is activated and until you turn it completely off via settings, the ALM stays solid and SNZ blinks.