They're moving AMC-16 from 85 to 118 and is apparently not a big deal. So why not kick E6 from 110 to 129? E5 is pretty much at the end of it's life anyways. Some day it'll crap out eventually, and then they gonna have to move one after all.
They probably want to make sure E10 is completely stable before they remove the backup. They really need E11 up with the steerable spots up to backup both E7 and E10.