That seat looks far scarier on a unicycle than the, to most male unicyclists, familiar numbness. Without a seat sitting between your legs I fear that it would be difficult to keep the seat from falling out back or to one of the sides. perhaps it could work if a handle was installed?
That said, in 2014 KH released the newer low curvature seat. It works wonders for me when it comes to numbness. Since it is has fairly firm padding and it’s firmly flat I now have the weight fully on my sit-bones rather than on that soft nerve-filled area. I haven’t had a problem with numbness since I changed seats. Though it seems that it takes some getting used to for some people.
There is a thread about the seat further down on the front page here.