Unlike deafness, cancer tends to be fatal. More appropriate comparisons (though not entirely comparable) would be gender dysphoria, autism, or, if the "gay gene" hypothesis is to be believed, homosexuality.
I don't think we should reject the creation of a medical cure at all. I'm completely of the view that if an procedure exists to treat/cure a problem (however that's defined to exist) the procedure should be available to the extent the creator is interested in providing it.
However, GP expanded upon a sociological dimension to disabilities and chronic illnesses that isn't usually discussed and considered. When asking "How do they cure it", an important question to consider is "Do they/ Would they ever want a cure and under what corcumstances?"
It's quite the coincidence that deafness was the example used, because the scenario GP describes actually happened once before:
