Fox engineers didn't design anything for the Grenadier. And it is also unfair to say there are no risks, because there have been people with the Fox stabilizer experience death wobble (if not posted on here, definitely on the FB groups).
The Fox stabilizers (both versions by Owl as well as the one Agile sells) are parts either designed for a generic application or another vehicle that have been adapted to work on the Grenadier.
Fox did not design the Grenadier kit, thus why it isn't available to purchase from Fox. There are kits put together by other companies using the Fox damper.
Additionally, "out perform" is an interesting phrase to use. The original vehicle is designed to with off-road driving and stability as a forefront; for which the factory damper is phenomenal. Any softer damper (like the Fox units, OME units, etc) will transmit more off road bump through the steering and into the driver's hands through the wheel, that's just basic physics and damper technology.