Tyson Fury wore tape over his mouth and refused to talk at a news conference to promote his heavyweight clash against Dereck Chisora on 29 November.
The protest was over a recent misconduct charge from the British Boxing Board of Control, who fined him £15,000 for comments made in June.
The tape had 'BBBofC' and question marks written across it.
The fight at London's ExCeL arena is for Chisora's European belt and the vacant British titles.
Manchester's Fury, 26, won their first meeting in 2011 and they were meant to have fought again in July, only for Londoner Chisora, 30, to pull out with a hand injury.
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Prior to the postponement, Fury launched into a number of expletive-laden rants at a news conference, directed at Chisora and a journalist.
Explaining his charge's protest, promoter Mick Hennessy said: "You need characters to be able to be themselves whatever they're confronted with.
"Sometimes you're going to get a gentleman with Tyson and sometimes, if he's rubbed up the wrong way, you'll get another side of him."
Fury, who has won all 22 of his professional fights, used his middle finger to indicate he plans to knock Chisora out in the first round.
Chisora-Fury II, which has sold 12,500 tickets so far, doubles as an eliminator for Wladimir Klitschko's WBO title.
Chisora, who has won 20 of his 24 fights, said he doubted his rival would be able to stay quiet until fight night.
"I think we could make a wager that he won't keep it on for the next eight weeks," said Chisora, who lost to then-WBC champion Vitali Klitschko in 2012.
"I'm going to knock him out, it's a simple fact. I don't know what round but I'm going to knock him out."