Are you rigging the Predator's eyes, mouth, etc... too?
Unfortunately no.
Sadly in Skyrim the speaking Morph targets are overly complicated and done with a completely different App - FACEGEN. Getting facial /head morphs working without that app was pretty difficult - but since you don't carry on any predator NPC conversations you don't really notice.
I'm pretty sure there is a way to do a manual job of it with blender and some tri strip tools from some very industrious people - but that's a lot of work that mostly won't show up (or if you were wearing a helmet - you wouldn't want it to show up - ie go through the helmet.
I might go poking around trying to get mouth morphs working again - but I've so many other bigger things I want to spend time on - like dungeons, AVP monsters and predator NPCs before I go back to dealing with the morph targets to get the mouth to animate.
The morph targets that I do have done are all body sizes morph targets. These are standard morph targets you can do in Studio Max without any 3rd party apps -- - so when you shift body weight sliders and the male and female avatars - all clothing and armor sizes change with it.