Calahan, you are partly wrong
The effect remains as you explain, but the reason you give is not correct
Rituals are cast in "random" order (not really random, but you know what I mean). There is no magic movement phase, there is just Rituals phase (during which rituals are resolved, be they moving, seeking arrows, assassination rituals or what ever), and then there is the Combat Phase after Rituals (when combat caused by magical movement take place). However, things moving with rituals *always* get to move unless they get killed or become feebleminded before it would be their turn to cast. Thus one can not prevent by Cloud Trapeze/telepeort/etc somebody using Boots of the Planes from always getting to move (Seeking Arrow, Mindhunt and assassiantion spells (like Earth Attack) might work though, if they get cast before the target gets to move).
Likewise, the fact that you can reinforce an army with magically moving commanders have nothing to do with "friendly movement". All rituals (inclduing magical movement) is conducted first, and combat caused by magical movement is solved after all rituals are cast.
EDIT: This is btw very easy to test and verify. Select two nations who can teleport/trapeze. Build a lab in the open for each, then on same turn there is a mage teleporting/trapezing from the lab to the opposing lab. Hey presto, both get to move, and then both fight whatever PD or other garrison there was left at the lab after the opposing mage had teleported out