And the arms race continues. I expect this will work only as long as law enforcement doesn't recognize it's a ram only box, after which they'd just keep it plugged in or drop it into liquid nitrogen to preserve the bits if they cared enough.
It will give a whole new meaning for when cops shout "Freeze!".
Dynamic ram refresh intervals are mindbogglingly conservative, especially if you're not running near the upper-temperature limit. In other words, DRAM doesn't lose information anywhere near as fast as the refresh intervals might suggest.