we are talking riding to avoid collision !!! so you could just forget about jumping then..
It would be the same in windsurf; you wouldn't jump if you 've got someone downwind of you
as he/she would be quite likely to received sail-board-and man in his face when you are landing.
Unless it's your mate and you want to scare the &*#$t out of him


As far as I know, the story behind the downwind dude priority in Sailing just simply come from the danger of the coast..
...if you are pushed toward rocks and you have to sail upwind to escape being crashed onto it..then any boat-sailor-kitesurfer- or sea gull should give way...SIMPLE!!!
Same stuff, if its a sandy beach instead of rocks.
I admit it could tricky in kite compare to sailing.......but there is a big advantage in kite: you could see pretty well what going on downwind of you as you 've got no sail in front of you.
Anyway If you don't want anyone downwind of you just ride faster!!!

...
or jump higher than his kite



not sure about that one!!!
leski