Odd choice for the cut off in that quote.
Apple A7 consumed 2560 mW to deliver 13 fps on iPhone 5S. An equivalent Tegra K1 mobile platform consumes
2605 mW to deliver 1.45x higher perform
ance. Since Jetson uses DDR3L and OS is not tuned for mobile, it
consumes 3658 mW to deliver an equivalent 1.45x performance advantage over Apple A7
So the jetson platform uses a full.... 1W extra, which is not massive at all and still puts it as a 9.8W platform vs other guys running much lower power.
It also shows in the paper for instance that it's delivering 2.5x the fps performance, but it's only 1.45x better in performance/watt. Assuming 13fps at(according to Nvidia 5.08fps per watt) then the A7 is using 2.55W, while the Nvidia chip is using 4.45W.
Either way this is Nvidia and they are rarely particularly honest about these things, losing most of the OEM industry who dumped design wins because Nvidia couldn't produce what they claimed. We'll see(hopefully) from some good reviews showing performance after a warm up period(Anandtech weren't particularly clear if they benchmark only after a warm up, they had a performance during warm up test, but I don't know if they then did each test at peak or throttled down performance, then the question is who will get a chinese tablet and benchmark it). Anandtech refused to do a K1 review when Nvidia refused to tell them the power usage, this is after Anandtech compared T3 or T4(forget which) to Apple's chip at the time and posted bogus power numbers Nvidia gave them. When they found out the numbers later on, their preview would have read completely differently.
I wouldn't actually be surprised if K1 was pretty efficient, they are using pretty much the latest process(further tweaked) and the latest and most improved version of A15. It's effectively using 18 months of improvements TSMC has made and that Arm has made on the process and core. Most companies could produce an improved 28nm chip, but everyone with half an ounce of sense is working to make much better, faster, cheaper A57 based 20nm chips.