I'm guessing it's the same reason why Kifaru doesn't "recommend" running the larger bags on the 22" frame. It won't be 'pretty'.
I got a 22" and 24" frame. I'm planning on running a mountain warrior, DT2, hc4800 and AMR on the 22". I figure if I put the tri-glides in the common loops on the bottom of the frame and cinch down the lower compression straps tight then it'll fit good enough. The tri-glides should help keep the lower delta strap in place too.
That's my theory at least. If it doesn't work then I'll be returning my 22" frame or hoping Kifaru comes out with a top loading 22" frame specific pack that doesn't end in "rambler"
I'm still on the fence about the 22 mag...