It's invisible only for the light of colors with photons with low energy, because the trick only blocks some interactions of the material and light.

If you use light with photons with more energy [perhaps ultraviolet] then other interactions are possible and it is visible.

So "invisible" is a simplification/exaggeration in the press article.

Agree it's an exaggeration, but still seems fascinating - that photons with the right energies go straight through, as if the matter wasn't there?! Does sound quite dark-matter-ish, but as someone else pointed out, the temperatures seem off. I prefer to believe dark matter is mostly something we don't yet quite understand about gravity/matter/space.

Physics is a highly speculative field due the limitation of our technology.

Physicists know this. But laypeople don't.

With the anti and pro science folks, this part is getting worse where you are called multiple insults for even casting doubt on any physics theory/law like "nothing can be faster than speed of light" or "energy is always conserved".