A Sydney man has been ordered to take out a newspaper advertisement publicly apologising to a prominent gay activist after a tribunal found his screams of "I am going to eradicate all gays from Oxford Street!" represented homosexual vilification.

But the same tribunal has rejected the activist's claim that when the same man assaulted him less than a week later, leaving him with severe facial injuries, this was also vilification.

Bashed: Simon Margan

Simon Margan, the Oceania representative of the International Lesbian, Gay, Bisexual, Trans and Intersex Association, was putting up posters supporting gay marriage on Oxford Street in August 2010 when Danny Manias, then 34, began following him down the famous entertainment strip.

"He appeared to be keeping pace with me even when I stopped to put up a poster which slowed me down, compared with the pace of the ordinary pedestrians," Mr Margan said in a statement to the Administrative Decisions Tribunal, which deals with most vilification claims in NSW.