It's already approved by ITU, just was not by FCC. In fact this Ku band is already used in downlink by Starlink as described in comment https://news.ycombinator.com/item?id=41662676#41664592
As those are the easy to license frequencies globally. Not to mention, 17GHz is far away from 12GHz and 14.5GHz, so the antenna complexity also goes up. And the teardowns of civilian Starlink terminals have not shown dual band antennas so far.