I dont think edge angle would explain why he cant cut news print. I keep many of my knives at 40 inclusive and they easily pop hair and do curvy cuts in phone book paper. I think i would rather keep zdp more obtuse for the sake of edge stability.
Any other, more typical, steel, I'd agree with you. Newsprint-slicing is pretty straightforward, with a crisp apex at even relatively wide edge angles. But ZDP-189 is a completely different animal, in keeping the apex crisp while refining it. The finer it gets at the apex, the more vulnerable it is to chipping and crumbling away with a slightly too-heavy touch on the hones. So, any issues with a heavy touch on the hones, especially ceramics, can dull the apex in a hurry. Making the apex crisp, in the first place, is what's more challenging with ZDP-189. If the apex isn't crisp, paper-slicing at 40° or higher basically stops in it's tracks. At thinner geometries, paper-slicing will tolerate some more dulling of the apex before the cutting stops altogether.
The fact that the OP has already mentioned seeing how different it behaves, as compared to other steels given the same treatment, is testament to the above points, and matches exactly what I've seen, and others here as well, in sharpening ZDP-189. A common complaint has been that it's difficult to detect burrs on ZDP, because they immediately break off instead of just rolling over (rolling makes them easy to detect/see/feel). So, with no burr yet seen, many just keep grinding (and grinding and grinding) looking for the burr, which seemingly never comes. That's why it's harder to refine, unless one is aware of the steel's tendencies.
I'm not a big fan of ZDP-189, for essentially these reasons. It's typically heat-treated to very high hardness, and therefore is very resistant to abrasive wear or plastic deformation (denting, rolling, etc). But it's extreme hardness comes with a trade-off of greatly reduced toughness and a vulnerability to chipping or cracking as the cutting geometry is improved (thinned). One basically has to choose between better cutting geometry, or better edge retention at a wider geometry that never cuts as well in the first place. So, if choosing better cutting geometry, the price paid is in reserving the blade for lighter uses (no prying/twisting/poking or heavy chopping), in hopes of not chipping, cracking or breaking it.
