I never heard him say "bio is only domain that is world-changing". But unlocking the genome would have unequivocal implications on quality of life and longevity for all of humanity, what is more important then improving someone's life?
People thought we were "unlocking the genome" ten years ago with the Human Genome Project. If that taught us anything, it is that biology is a lot more complicated than simply parsing data. Biology is messy, complicated and breaks every single one of its own rules. Repeatedly.
I'm not saying bioinformatics is unimportant or unnecessary, because it truly is important. I'm simply tired of people (particularly famous people who are grandstanding) boasting that XYZ will "cure cancer".
Plus publicity stunt of quitting so you'll listen [at 14:15, sounded like quitting a cat-photo-sharing project, rather than quitting Google].
Plus implication that bio is the only domain that is world-changing.