I don't want to rain on your parade and this is my opinion, but what's the point in having that if you already have a gun safe? If someone does break in I doubt you're going to be able to fumble around quick enough to get it unlocked in time.
Unfortunately, I also don't have an alternative for you. It sounds like you want to keep a shotgun at the ready, but not ready enough for your son. That's tough, but I don't want to see you waste your money on this.
The one other major problem I see about this is the lock. It appears to be a trigger lock. I don't recommend storing shotguns with one in the chamber anyway, but if that's how you keeps your now I would not use this lock. Never use a trigger lock with a loaded firearm.