The FAQ, while answering a few of my questions (like the interaction between Rain of Pus and Soporific Musk, we played that right it seems), made me wonder:
If a controlled (formerly enemy) figure is summoned away by the Slaanesh player, it no longer is under the influence of the Soporific Musk (FAQ page 3). On the other hand, Tzeentch can Warp Shield and then Teleport a figure, which results in the figure being protected by the Warp Field in a different region than it was previously, and consequently in a different region from where Warp Shield was played (Rulebook page 14).
The combination of these rulings makes me believe that if the Tzeentch player were to Warp Shield one of his figures, and then summon it away to another region, the figure would lose the protection from the Warp Shield as well - making it necessary to have and play a Teleport if he'd want a Warp Shielded figure moved into the target region, even if the region is one (or adjacent to one) in which Tzeentch has figures.
Is this correct?
I slept over this and was about to make it a rules question, after realizing that "move" and "summon" really are the same thing (rulebook page 11) and thus my attempt at finding an explanation for the difference was misguided from the start.