Any IAP is laid out for normal configuration e.g. all engines operating.
Yes, they say that but it doesn't mean anything. If you can maintain the minimum missed approach climb gradient then that's all that matters. It doesn't matter if you've lost one engine or two engines or you're flying a rocket or you fire a cannonball - the object (whatever it is and whatever happens to be propelling it at the time) will not hit any ground object if it can maintain the minimum missed approach climb gradient.
The only reason a designer will say that it's only laid out for normal operation of the airplane is so that they cover their ass for whatever litigation they might encounter from an incompetent company or pilot who decides to sue because it didn't say on the plate that they should double check their performance if they want to attempt the approach single engine.