The issue is not with textures, that is understandable. I think that is pretty clear in the EULA.

What I want to do involved using heightmaps obtained from rendering posed figures to create reliefs (essentially sculpture viewed from one side only) for CNC machining. There are no 2d textures involved. Any surface patterning would have to created in the geometry.

The geometry from the original figures is not used, or transferred, to make the relief. So the 2d render only is used and the result, while superficially similar, is not at all the same. The is true for ads, illustration, animation, or whatever anyone else is doing commercially with their renders. They are not reselling the product, they have used it in a different form.

So I asked Daz to correct their EULA to reflect this new information that they gave me about heightmaps used to produce 3d models violating their EULA. They refused to acknowledge there is a problem with it.

So if they are not serious about correcting problems, then they must want the EULA to be non specific. Companies try to do this all the time, particularly in the area of patents, where they try to get the broadest interpretation patented. However, proprietary work requires specifics, and if they can't specify it, they can't own it or claim rights to it.

Therefore, their EULA is flawed. They certainly can't make up new conditions afterward. If they want to correct the EULA to state these limitation as they come up, thats fine, make it clear to users. But don't go charging anyone with violating the terms if the terms are not there to begin with.