[bijection]

The linked article covers this - the main innovation is neither the HIV activation treatment nor the general mRNA-wrapped-in-lipids (LNP) delivery mechanism. Instead, it's a new form of LNP which works on specific white blood cells that were hard to target before.

  It was “previously thought impossible” to deliver mRNA to the type of white
  blood cell that is home to HIV, said Dr Paula Cevaal, research fellow at the
  Doherty Institute and co-first author of the study, because those cells did
  not take up the fat bubbles, or lipid nanoparticles (LNPs), used to carry it.

  The team have developed a new type of LNP that those cells will accept, known
  as LNP X. She said: “Our hope is that this new nanoparticle design could be a
  new pathway to an HIV cure.”