Seriously though it is because Goldberg is one of the faces of the years WCW put WWF on the brink of annihilaiton. I think anyone that didn't jump ship before the acquisition or anyone that is largely considered to be associated with the WCW is a persona non grata. Look at Goldberg in 02/03, he was essentially a tool to raise HHH up higher, DDP was turned into a stalked, Booker T was made to look awful at WM19, Bagwell or whatever he called had one appearance, and some of the others whose contract was owned by Time-Warner instead of WCW refused to join WWF on a smaller pay so I imagine that infuriated McMahon even further, especially since they were people like Sting, and former WWF employees like Scott Hall and Kevin Nash.
It was a clusterfuck, the ego of it all ruined the Invasion angle; which properly cooked and prepared would have been m o n e y.