The Dover Post reports that Stamos told Probst that he sat down with GH brass but didn't like the idea they had for how his character would be involved in the show. He said they wanted Blackie Parrish to play the drums for Rick Springfield while he sang "Jessie's Girl" at the Nurse's Ball. Stamos would prefer a "meatier role" though.
He told Probst he passed on the concept, adding:
"Why don't we pull Blackie out of jail [where he's been for 30 years] and he has to reacclimate to life? He's never been with a girl! I would like to go on [GH] and do some acting."
Blackie Parrish was part of the GH cast from 1982 through 84. He was taken in by Dr. Rick Webber and his wife Lesley, and helped develop a community sports center for kids to hang out in, rather than getting into trouble. He also formed "Blackie and the Riff Raff" a band he was the drummer for, which Frisco Jones was eventually brought in as the singer for. Blackie and Frisco would become roommates at Port Charles Hotel for a while too. Later on, an incident occurred where Blackie's former girlfriend, Lou Swenson, died trying to confront Blackie over a song he stole from someone else. Eventually, Blackie claimed responsibility for the death which saw him sentenced to prison for manslaughter.
Along with Rick Springfield, Jack Wagner, and many others, John Stamos is also one of the big names synonymous with Port Charles and General Hospital so seeing him return back would be great. However, it sounds like either he's throwing up a smokescreen to prevent people from a surprise appearance on the GH 50th anniversary, or he really won't be there. If he were to return, wouldn't longtime fans want other classic characters or actors back as well? Demi Moore would certainly be among those on the list as well.
So for now, it seems the General Hospital spoilers are saying John Stamos and Blackie won't be back to Port Charles, unless a big surprise is in the works!