If I were a member of management, and I found out that he was doing this, I would be furious. Not because he gamed the system and received the bonuses, but because he didn't share his innovation with the rest of the team and improve everyones' efficiency. If he had done that, I would recognize his talent and initiative and promote him, allowing him to do more rewarding, higher-level work.
If I made a script that deals with 98% of all of my work I could not imagine not sharing that with my bosses. To me (and I'm sure lots of people don't share this sentiment) it would feel morally wrong not to.