Can't an ejection from anything kill you? Still, I see your point. It was explained to me that you had to be good to go for 2 out of 3 platforms. My NAMI letter never said which ones for me, but the doc at OCS said he thinks it was my sitting height keeping me out of jet and helo trainers. I don't remember my measurements. I could see how the ass-knee thing could be signed off on, but if the canopy won't close and en the seat is all the way down, there is nothing they can do I guess. I suppose that sitting height is probably non-waiverable then.
Eh, they like to say if you eject inside the envelope there is a very high chance of survival. They aren't giving out ejection seat waivers right now.