He told the Herald: "I feel revulsion and disappointment towards Harvey Weinstein, but as is with so often the case with Twitter, those seeking to be outraged leapt to attack anyone who doesn't comply with their group think."
Wednesday wasn't the first time the 53-year-old former reporter and radio host drew criticism for a social media post.
The Electoral Commission confirmed on September 26 that it was looking into one of Plunket that used a play on words to endorse the political party he worked for.
The commission confirmed it has received complaints about the tweet, which read: "Hope everyone remembers to put a top on before going out to vote, when it's cold, two tops."
Plunket has released a statement saying he chose to resign from his position at the BSA "in the interests of the smooth running" of the authority.
"I wish the Board well in its important work in ensuring that the broadcast media in this country adhere to practices
which do not harm society in general or individuals in particular," the statement said.
BSA chairman Peter Radich said the authority respected Plunket's decision to resign in the best interests of the authority.
"Sean Plunket is an experienced journalist and broadcaster whose contributions are part of the recent fabric of broadcasting. We wish him well for the future," Radich said in a statement.
The authority's members are appointed by the Governor-General on advice from the Minister for Broadcasting.
The BSA yesterday confirmed to the Herald that it was reviewing Plunket's tweet.
"We are aware of it," authority chief executive Belinda Moffat said. "The board is considering it. They are giving it urgency."
"They will be considering the matter carefully and dealing with it in an appropriate way."
When asked what powers the board had to act regarding Plunket's comments on Twitter, Moffat said, "It's not appropriate to comment on the process."
Plunket has also quit Twitter.
He told the Herald he voluntarily stood down "because circumstances meant that my continued presence on the board was impinging its ability to fulfill its jobs and for the BSA to do its important job".
When asked whether the circumstances in questions were related to the tweet about Harvey Weinstein, Plunket said "not necessarily".
He refused to comment further about the circumstances surrounding his resignation, saying he was not at liberty to discuss them.
"The BSA's got an important job to do. It became apparent to me that my continued presence on the board was impinging its ability to do that job and as anyone who's on the board of an organisation knows, it is the organisation that must come first."
Plunket would not confirm whether he would return to Twitter, saying "that's of no public interest whatsoever".
"I have the greatest of respect for the BSA, the institution, the other board members and the Minister," he told the Herald.
He is no longer working with TOP and said he would return to his consultancy business.
