The INJ is not making the eyebrow visible, I think the tester is turning on visibility manually and are pointing out the fact it does not conform to the head morph.
Why is the tester turning on the eyebrow prop to test your morph? It will NEVER conform to anything but the default M4 because the prop does not have any morphs to conform to. You don’t even include the eyebrow prop in exporting the head to even make a morph, unless you want a vertex order issue when you try to import it back. This is similar to having to make a fit pose for the gens because the gens only have a limited set of conforming morphs and if you use any morphs other than what’s in the gens, you have to manually adjust the position. It’s very rare that you’d find eyebrow textures for the male anyway, that’s why it was eliminated with Genesis. I’d bet if you look at any other custom head morph on that site, you’d see the same issues with other M4s that’s actually made it into the store.
As your texture already has eyebrows and you have not enabled visibility on the eyebrow prop, I’d ask the tester exactly why he’s testing whether a static eyebrow prop without morphs is conforming to a custom head morph where a texture with eyebrows is already being provided.
It sounds like a bit waste of time on both your parts, and something the tester shouldn’t even be looking for.