Itachi understood a better than Sasuke did. He also knew that, for healing, chakra could be a godsend, but at the same time, any part of him that had been healed by chakra had eventually reverted back to its diseased state. Chakra could heal the damage, but it couldn't prevent it from happening again.

All the shinobi medics said nothing could.

But this man was offering a different approach that just hadn't been tried. And Itachi was open to that.