Schaeffer has been battling the High Court lawsuit bought against him by James Murren and Daniel Lee for three years.
Murren is chief executive of MGM Resorts International, a multi-billion dollar Las Vegas hospitality business, while Lee is also the boss of a casino company in the same city.
Murren and Lee, in court documents, say they and others discussed forming a partnership with Schaeffer in 2002 that would own a vineyard and winery.
They say Schaeffer, who formerly headed the Mandalay Resort group in the US, sought capital contributions from them for the proposed partnership and when doing so either stated or implied that they were part-owners of the Woollaston Estates Vineyard, which later changed its name to Mahana.
They allege that Schaeffer, after 2008, made further representations to them that they were part owners of a vineyard and winery in New Zealand.
Murren says he and his trust have personally paid Schaeffer US$1.6 million while Lee says he paid US$700,406.
Murren and Lee allege the representations made to them were false and say the payments they made were not used to make the investments promised but instead for the assets he holds as a shareholder of New Zealand company Woollaston Estates Holdings.
The pair's case alleges the representations breached the Fair Trading Act, that Schaeffer breached a duty of care he owed and that he knew the representations were false.
A 10-day hearing for the case is scheduled to begin next month.
But Schaeffer made two bids this month to halt the action or delay it.
He alleges that last year, during a mediation to try to settle the dispute, Lee threatened him.
"He knew where I lived, knew where my family lived and knew where my dogs lived," Schaeffer claimed.
"He said if I did not give him back his money that he would bury me in the desert like in the old days, he would destroy my children's lives and bankrupt my ex-wife and travel to Omaha to kill my three show dogs. He ended his threats with the words 'give me my f***ing money'," Schaeffer said Lee alleged.
Lee disputes Schaeffer's account.
While he told Schaeffer that Las Vegas gaming executives in the "old days" might have ended up buried in the Nevada desert, after saying this he claims he pointed out that things were done differently now and he had come to the mediation to settle the lawsuit.
He denies threatening Schaeffer's family or show dogs and Murren supports Lee's recollection of what was said.
In the Court of Appeal today, Schaeffer's lawyer Andrew Butler asked the court to consider whether it was appropriate to continue with the lawsuit at this stage, given Schaeffer believed he had been threatened.
He also said Murren should have condemned the alleged threats and made it clear such comments were "completely unacceptable".
"Mr Murren gets the benefits of the advantages of the threats that are made by Mr Lee," he said.
Lawyer for the respondent, Andrew Horne, said there was no reason to adjourn the trial.
He said Lee was a well-respected businessman in a highly regulated industry, with a great deal to lose if he was to do anything "untoward".
The latest application was part of a "campaign" designed to avoid a trial, he said.
The alleged threats were made more than a year ago.
After a brief discussion, the Court of Appeal judges agreed to dismiss the appeal.
The trial will go ahead.
