The unexpected revelation was revealed by screenwriter Mark Bomback during an interview with an interview with CreativeScreenwriting.

According to Bomback, an early version of the film would have also featured Anna Paquin's X-Men character Rogue:
"I love Rogue and I just think that there’s something about this idea that Rogue is tremendously empathetic but incapable of safe human contact,"

"I was trying to do something with Rogue in the script. I even had a set of ideas that the old man possessed a version of Rogue’s power and that was going to be indicated by a white stripe in his hair."
As for why the idea was shelved, Bomback explains:
"Eventually it became very goofy, and I threw it out because I started realizing throughout the script that it became more problematic than cool. It’s no accident to me that in the first X-Men film the first two mutants that you really see who have a connection are Wolverine and Rogue. There’s something special between them, so I was trying to bring Rogue into it, but it just didn’t get there. I regretted there wasn’t a way to figure it out, but when I look at the film now, it would have stuck out if we tried to shoehorn her in there just because it was another character from the universe."
Here's hoping that Rogue does return to the big screen one day because her character is just awesome!