Richard Catto makes money through banner advertising; in fact, he seems to have a company "Adderleystreet Advertising" for this. Thus his hate-filled flaming probably also partially has an economic motive, to drive hits to his website, where he then seemingly sells "impressions" (i.e. pageviews, not clicks) - cf.
this. Adderleystreet customers - his advertisers - are in effect sponsoring the promotion of genocide. This may on their part be unwitting (in which case they would hopefully want to withdraw their advertising), or worse, purposeful. I thus suggest anyone else who feels strongly about the advocacy of genocide against their or other peoples write to the sponsors too to let them know how you feel about this, and that their supporting of hate speech may be illegal in South Africa.