Just curious and I have never messed extensively with Poser's Hair Room (Because it's Poser's Hair Room) and haven't used Talk Designer. But..

Do you think the following will work - Copy the underlying geometry. IIRC, the brows are a rigged bit, so you can target them for export. Import that object, grow your brows, parent it to the Brow rig. Done.

It's likely Talk Designer can't see the dynamically generated brows as a rigged object and won't animate it. If so, it may not recognize the parented object's relationship to the rig, either, thus not moving them. In that case, it has to be rigged separately as a "Figure" and conformed. Even so... I don't know enough about Talk Designer to deal with that if it inserts custom animations. That's a Talk Designer thing and may require special secret knowledge stuffs...

But, the thing is we're tied to the limitations of Poser's Hair Room system and what it ends up producing. As you note, as soon as you save a "Rigged" dynamic hair object... you may as well slit your wrists. What you could do, I suppose, is create the figure for it, save that figure with no dynamic hair, then when you need rigged dynamic hair for Talk Designer to muck with, you load up the prop/object hair you've generated and then go into the Setup room, open you Library to the rigged version of it that doesn't have hair and double-click. That will apply the rig to your otherwise static hair object, provided it has a standard mesh to reference as the base. Exit the Setup room and there's your ready-to-use rigged eyebrow object... Dunno how useful that workflow would be, though, and you can't "save" it like that, else it makes Poser angry.

(The Hair Room is one of those things everyone wants improvements for.)

Last - Standard transmapped hair can be pretty darn complex and yield good results. Not worth it for you? Talk Designer can't deal with it or something? Also - Someone produced some actual polygon "body hair" for Poser figures. This is hair that isn't in Posers two-dimensional sort of Strand format. It's actual polygons. (Same guys that did the custom V4 JCMs, IIRC.) That could offer a solution for you if it includes eyebrows. I don't see why it wouldn't and, in any case, it gets you out of the Hair Room Problem and into "polygons" which are less trouble.