Some on here will remember Crawford Carrick-Anderson from his SSDT days. He too, was deaf and a damned good rider (and a great ski-er). Last I heard of him downhill mountain biking was his thing.
Personally, I believe it's due to their other senses being more finely attuned. They learn through feeling the bike rather than listening to it and, as such, it becomes more of an extension to their bodies rather than a seperate entity they're fighting to control.
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Disclaimer: This may, of course, be total bollox.