The fan in question was a local morning DJ, Cam Carson, who works for Winnipeg radio station Power 97. The station had been promoting the show and was listed as a sponsor for the event.
Batista began jawing with Carson before the match and when he turned to return to the ring, Carson hit him in the back/shoulder area, according to one fan that was sitting nearby. That led to Batista forcefully shoving him down. Carson tried to get over the rail but was stopped and spoken to by security - yet allowed to remain. Batista then began wrestling Big Show in a singles match.
Later on, Batista flipped the finger to Carson as he passed him while circling the ring. That led to Carson "losing it" and trying again to hop the rail, at which point he was walked out by security.
Whether this was a publicity stunt or something legitimate we cannot confirm, but my gut is it's the former, even if no one immediately admits it. But, we'll have to see.
WWE performers physically interacting with fans in an aggressive way calls for a fine from the company. Last year, Mark Henry once claimed it was a $10,000 fine during an interview.