Pure B.S. I was the Senior product Manager for IL-3 and IL-6. Most interleukins (1-12) are highly toxic in doses needed to have an effect. I would highly doubt you will ever see medical use of IL-6. It was also studied for a supposed anti-tumor effect which did not exist.
They’re not talking about administering IL-6, but drugs to block its effects. Such might be effective and safe enough for some conditions.