Just my two bits on it...

Starting with the assumption you have a 3d obj that you got a general commercial licence to use in createing images, art, etc.  But speciffically prohibits reselling the geometry itself (which is what the copyright actually covers).  As I understand copyright law, you could use that mesh to create a 3d printed object and legally that would be no different than creating a digital image for commercial use... you aren't actually distributing or reselling the geometry so copyright isn't an issue.  Same as if you use it to create a digital pic, then use that pic to have printed art made, or graphics on a t-shirt, etc.  The physical model doesn't contain the obj geometry and its the specific geometry that is copyrighted (copyright law requires that you copyright something very specific, so for example to register the copyright for V4, DAZ would have had to submit a copy of the obj geometry to the copyright office which keeps a copy on file and that is what the court will compare too in determining if copyright infringement has occurred.  Since we do have a license to use V4 in commercial art, and since a physical object doesn't contain the geometry mesh, its not copyright infringement nor is it a derivative work, however, see EULA's below).

However, then we get into EULA agreements.  EULA agreements can pretty much specifiy anything they want and its binding.  So say someone makes a 3d obj mesh and includes a EULA that says you can use it to create any form of art provided you don't violate the copyright (resell the obj mesh itself) and at no point color any part of the object blue.  Weird as that may be, its legally binding.  Or you could make a model of your girlfriend, sell it and specify that it can be used to create any sort of digital art, so long as it does not contain any sexually explicity content... and its legally binding, your virtual girlfriend won't be making digital porn (at least not legally).  So if DAZ has basically said you can't use V4 for 3D printing with out more or less going thru DAZ in the EULA, you're stuck with that.  EULA's allow you to place pretty much any restriction or reserve any right you (as the creator and copyright holder) might wish.  It can get pretty weird, I've seen EULA's that, for example, allowed almost anything but stated you couldn't post images created with the content to a certain web site... apparently the creator didn't like that specific website and didn't want any of their stuff used in art there... guess what, its legal to do that... annoying, but legal.

As far as the idea that someone could rescan the printed 3D model and somehow recover the 3D obj mesh... no, they couldn't.  First, 3D printing requires post work that will somewhat alter the topology of the figure (from what I've seen, they have to smooth it out because the printer leaves lots of rough spots), once that's done you've got a prototype you can use to cast molds from for production.  Even if you scanned that, you wouldn't get the same obj geometry.  A good 3d model has a mesh with vertice edges that follow the contours of the body.  But a scanner will generally just give you straight rings looping around the figure.  Plus the polygon count itself would be different.  Try using that mesh and it won't deform the same way as the original figure, you'll get noticebly different results.  Also that scanned mesh won't include any rigging, morphs, etc.   So the idea that someone will copy the figure and somehow "steal" the work of the original 3d modeller is just silly, can't happen that way.  It would take a lot of work to recreate it and that would cost someone way more money and time than just spending the $50 and buying a copy of V4 directly from DAZ
Now personally, if I were going to try my hand at 3D printing from a 3D model, I'd skip Poser and Poser content entirely.  I'd shell out for 3D Studio Max or ZBrush, go to a professional 3D model vendor (exhchange3d for example, which in their standard license explicitly includes the right to use the model in 3D printing) and buy a much higher rez model than V4 that doesn't have any restriction about 3D printing and have at it.  Which is, from what I understand, exactly what most trying to do this are doing.

Someone mentioned that as the technology for 3D printing becomes more common place, this will all shake out and I think that is true.   I really don't get some of the crazy EULA agreements I've seen in the Poser community, sometimes it just seems plain silly or greedy or paranoid.  But, if you buy something that comes with a EULA, you are bound by it.  Even if it seems or is really dumb, you agreed to it so deal with it.  If you don't like the EULA's of a specific vendor, buy from someone else.