Weinstein's brother and business partner Bob told The Hollywood Reporter in an emotional interview published Saturday that he knew the tycoon was a cheater, but said he was unaware the extent of his "sick and depraved" behaviour.
"For me, I thought he was literally just going out there cheating in a pervasive way," he is quoted as saying.
"It wasn't like he even had a mistress. It was one after another and that I was aware of.
"But as far as being in a room and hearing the description in The New York Times? No way."
Weinstein appears to have garnered little sympathy from the public, either, according to a survey conducted by celebrity branding expert and bestselling author Jeetendr Sehdev.
Some 82 per cent of 2,000 people questioned as part of an ongoing study into American attitudes to celebrity and entertainment said he should be kicked out of the Academy.
Hollywood, too, has largely turned its back on Weinstein, with veteran filmmaker Oliver Stone and fashion designer Donna Karan offering the only words of support.
While Stone merely warned against Weinstein being "condemned by a vigilante system", Karan went further, triggering outrage when she suggested women had been seeking a reaction from Weinstein by dressing provocatively.
Expulsion is a sanction the Academy had used just once before Weinstein, according to The Hollywood Reporter, against "The Godfather II" actor Carmine Caridi.
He was accused of giving tapes of around 60 Oscar movies seeking consideration for the Academy Awards to a neighbour who turned out to be a pirate.
The LA Times newspaper reported that some members of the board had wrestled with the Weinstein vote, worried that it might set a precedent requiring governors to police members' behaviour.
Other A-listers including Bill Cosby, Roman Polanski and Mel Gibson have all been investigated for their treatment of women but have escaped expulsion.
Celebrities took to Twitter to celebrate Weinstein's expulsion, with "Hellboy" actor Ron Perlman declaring how "proud" he was of the decision.
Mia Farrow, who worked with Polanski on "Rosemary's Baby" (1968) voiced hope that "we are witnessing the end of an awful era" while cautioning that "there are others".
Weinstein's films have received more than 300 Oscar nominations and 81 statuettes, according to The Weinstein Company, which he co-founded after selling Miramax.
The studio fired him on Sunday and is exploring a sale or shutdown, according to the Wall Street Journal.
Meanwhile the producer's wife, English fashion designer Georgina Chapman, has said she plans to divorce him.