I don't have the books in front of me, but I suppose this means you can have a knight using a ki focus that shifts people on an MBA. I recall making a knight who had +3 or 4 to the amount of squares he pushed people. Some of that was from/for a weapon. I think that some or all of those bonus squares also applied to slides.
So if you have a knight with Hammerhands stance (pushing one) hitting a guy with an MBA that slides people. That could be devastating if you get to double dip on the feats that add +1 to the amount of squares pushed or slid.
How would you apply that? Does it slide then push, push then slide? Seems like an awful amount of battlefield control.
Even at its most basic, just getting Battering Shield, that is +1 to slides/pushes. Being able to slide somebody two squares, then push them 2 squares would be pretty amazing. A push after a slide is almost as good as sliding itself.