Good idea.
The problem I see is that they weren't banished to the lands of their enemies, they were just plain banished- Islamic lands were just the best choice of where to go for them.
When you try and move them like this most would probally choose to head to North Africa anyway.
Exactly. If given the choice to flee to the nearest non-hostile ports it is clear that the Moriscos would add to the might of the Maghreb if one thinks about it, so the idea was to place them where they must cling to the Spanish Authorities or be at the mercy of Hostile Christians.
The error was presumption of severe hostility on the part of said Christians.
HTG