Cardboard's ignition point is above 400C. Computer components don't do well running above 80C. Something would have to go horribly wrong for a computer to ignite cardboard. Cardboard just seems easy to ignite because it's commonly burned with a butane lighter that burns at over 400C as well.
I've got an i.MX6Q bare board running next to me. It's beefier than this book PC (quad A9s instead of one). It has no heatsink and gets only slightly warm to the touch after running it hard for a while.
If any excess heat is generated by this thing, that aluminum backplate can probably sink it.
As for UL certification, this thing is low-voltage DC only. The power brick should be certified but that's probably all that's needed. And FCC class-B like usual.
It's a modest step up from the imx5, and OMG MORE COREZ. We're looking at it more for a cost-reduction move from the imx53 than a performance gain.
Freescale got the hint and put a lot of the voltage regulation on-board so there's no need for the external PMIC anymore. That was always the dirty little secret of these SoC chips, you needed the companion chip to make it complete...
EDIT: Would that ever get a UL seal? I wonder!