You realize that only works if someone has PHYSICAL access to the device with the cold storage? With physical access, it's easier for a thief to steal the wallet file, regardless if it had internet or not.
Cracking the password to the wallet is another story.
Physical access is not required in many cases. Since 2009 (32nm Sandybridge) all Intel CPUs have vPro AMT built in, allowing anyone to control the computer remotely using wireless 3G technology. There are remote exploits in the wild and the technology cannot be disabled by the end user, the setting to disable AMT in the Bios is ignored.
"Currently, Intel AMT is available in desktops, servers, ultrabooks, tablets, and laptops with Intel Core vPro processor family, including Intel Core i3, i5, i7, and Intel Xeon processor E3-1200 product family"
http://en.wikipedia.org/wiki/Intel_Active_Management_Technology"AMT is designed to help sys-admins remotely manage and secure PCs out-of-band when PC power is off"
http://en.wikipedia.org/wiki/Intel_AMT_versionsKeywords are "out-of-band" and "when PC power is off". The Intel CPUs are always on, even when they are off, provided the computer is plugged in to the power. They can remotely access all your data anytime they wish, without permission and without anyway for the end user to disable this "feature". It is well documented, so there should be no surprises here.
same thing with your ip television. you can have ur tv turned off but the tv is still getting power and can still be used by NSA hackers to monitor you eating your bowl of #ebolas in the morning..
to circumvent this problem i use a voltage regulator between the wall outlet and the surge protector and cut the voltage regulator power when tv is not in use.
the voltage regulator will save you from coming home and finding your tv doesnt work anymore because of dirty power as well .
you should disconnect your internet modem when not in use (keeps hacker neighbors from getting used to stealing your bandwidth).
and only use hard wires in your home network disabling the wireless in your router until needed.