There's not a single ready anim, there are multiple different ones to cover the different weapon types. You can use @JCarter426's combat animation guide and TSL's annotated animations.2da to help you find them, but they should be of the form gXrY, where X and Y are numbers that indicate wielding type and anim variation, respectively. For example, g2r1 should be the single saber/sword ready and g5r1 should be the single blaster pistol ready. Some of these appear to be recycled, for example g7r1 (rifle) and g9r1 (heavy carbine) are identical. If you are setting the piggy's anims as unarmed, then they'll presumably need a g8r1 for the ready anim. But since their UTCs force them to use melee anims, I'd just go with that. They obviously already have a limited set of anims by default, so duplicating the existing ones to cover the melee variations shouldn't be too much of a problem. The only question is whether the choreography limits the human anims when fighting a creature, or if it uses the full range of anims regardless. I'm not sure I ever noticed.
There's nothing special in the DLG that would suggest the cause. Neither it or the ambush one have any forced or scripted talk anims. I'm not sure why it would work in one scene and not the other.
You can export and import a text list of the node mapping, so it might be worth doing it that way to see if that gives you some more control.