RoE:
"The animal companion gains all the benefits of
shifting (including any shifter feats or class features
in effect for the shifter ranger), though it does not gain
any new natural weapons."
And then the bit you quoted from ECS seems to imply to me that it's a special kind of shifting, but shifting nonetheless, so I'd say yes as well
Assuming you're correct though, wouldn't the AC be able to turn into the same animal/hybrid the shifter turns into?
Either way, keep in mind Weretouched Master got a pretty big nerf in the errata