Phobia - "a persistent fear of an object or situation in which the sufferer commits to great lengths in avoiding, typically disproportional to the actual danger posed, often being recognized as irrational."
Bill's point is that 'homophobia' is used as a label for all people who do not agree with homosexuality as a lifestyle. It has nothing to do with an 'irrational fear' of homosexuals. It's meaning has be morphed far beyond it's original definition. Unlike the word gay, whose definition has also been morphed beyond recognition, phobias are medical/psychological definitions and as such are not 'common' English.