They might not pay him much, but keeping his quiver full is a cheap way to ride redbull's coattails until/unless he finds a kite he likes better than the fuel.
Redbull pushes a lot of footage and burns it into the target customers' brains, if SS loses him, probably their loss. Any groms signed would be years from delivering that kind of value. Lenten is almost like the Laird of kiting, mainly seen as a specialist, but undeniably more of a badass than many on the tour. And he is still fairly young.
FWIW, to my knowledge Ruben never ran 5 lines on his fuels, at least not the 7's + 9's he used for big airs and loops.
He did use the ATL system to reverse relaunch (from beach at least) the fuels up to and including the 2007-2008 ones. By 08 the smaller fuels would reverse relaunch in strong winds, by 09, as is well known, SS expanded the LE tube and wingtips to let all sizes reverse relaunch.
Anyway if he does move to another brand, he will get them to improve their C designs I bet!