I'm confused as to where this even becomes a problem... The mechanics are quite clear as to what happens. If the fluff ever leads to a contradiction, then the fluff is wrong. It's only when the mechanics lead to a contradiction that something is wrong. It's very easy (as shown above, which I was going to show) to make more sense of the fluff when it is wrong. Slide is forced movement, it isn't a voluntary thing. Thus, Command clearly is not something done of their will, and thus is not subject to normal restrictions on movement. Cause Fear, however, would be restricted by immobilize, since it causes the person to "move", which is a "voluntary" (sort of) action that is subject to the normal restrictions on movement (e.g. immobilized)
Also, on the subject of grabs, it says in the grab section that if either you or the subject of your grab gets moved out of the range you can grab (forced movement), then the grab ends.