"He said personal reasons. We're not going to push it," Winfrey told THR of Vick, who spent a year and a half behind bars on dogfighting charges.
In his place comes Arquette, who recently completed a month-long stint in rehab for alcohol and emotional problems.
Arquette revealed intimate details of his relationship with Cox, talked about post-breakup trysts and copped to bouts of excessive drinking.
"I've been drinking a lot because I'm heartbroken," he told Stern shortly before heading to rehab. "It's really a personal, traumatic thing."