From article:"Wilma Cline, 42, and her husband, David, 41, who claim they were Limbaugh's drug suppliers from 1998 to 2002 and that he paid them tens of thousands of dollars."
If it supposedly began in 1998 that would have been before Rush's onset of hearing loss.
Also if I recall correctly it was not a genetic hearing loss. It was caused from a virus that had not been treated soon enough with anti-biotics.