Why do you think someone who wrote a song that insults mental health, suicide, HIV and homosexuality would draw a line at racism? I personally don't believe the Iscariot link. I think it is used as a tedious link to justify what has happened.
Say, for instance, the defence that the reference is to Judas Iscariot. Under scrutiny it is a pretty weak alibi. A single character that may or may not have existed, and may or may not have hung himself, in a book that has for centuries been used to justify heinous crimes. Compared to the well documented history of lynching of slaves in America, something that is taught on the national curriculum in this country, the Iscariot theory seems to have holes in.
Do you honestly think every person that sang the song in question was thinking of Judas Iscariot? I don't. The person who came up with it may have had that reference in mind, but once other people joined in, their interpretations may have differed.
We may have drifted off the original topic slightly here. I don't think the reason Campbell was looked over for the captaincy was his race, but he is a player who had received racial abuse during his career.