I don't see how it could be. It is not up to GameStop to drop the charges, it is up the prosecutor. Their wishes would be taken into account by a prosecutor, but not to the degree that the prosecutor would let them dictate a plea bargain. And whatever level of consultation the prosecutor chose to have with them, it would be highly improper to have the victim negotiate a plea bargain with the defendant.
The only thing that GameStop could offer would be a dropping or settlement of civil charges. Which would probably take place after a criminal trial.
It seems like the likeliest possibilities are
a) The calls were made right after the incident, maybe even before he was arrested. Maybe an attempt to get him to return to the store to talk to the police or something.
b) The calls were made to formalize a ban. Perhaps the previous bans were just a manager saying "Don't come back anymore" and they wanted to make it a little more official and formal.
c) The calls were made to inform Chris of something like the medical bills for the employee who was maced. Some cost that they feel Chris is legally on the hook for that they hope they can convince him to pay without suing him. Good luck to them with that.