Zerglite.. shh.
As for your question, I'm not sure if Insane Zerg Campaign Expansion forces them to go nydus or not. I've never seen it either, but part of the problem could be lack of creep to nydus to, or lack of sight at the location. If you're not making a melee styled map with Campaign AI, I'm not sure how to force units to use a nydus, or if it's even possible. I had to do that on a map once, and I just put a location on Nydus #1 and another location on Nydus #2. I had a trigger like
Conditions
-
Computer brings at least 1 men to
Nydus #1 Location.
Actions
-Move all men for
Computer at
Nydus #1 Location to
Nydus #2 Location.
-Preserve trigger.
Then just use triggers or some such to get them to move to the location over Nydus #1. In the meantime, I'll find out if you can force units to actually use a nydus.