Rio tickets fiasco is still a head scratcher

A man, Kevin Mallon, who works for one company, THG, voluntarily decided to act as a ticket agent for a rival company, Pro10 Sports, in Rio, to help them distribute almost 800 tickets. He ends up getting arrested amid allegations of ticket touting.
Question one: Why would anyone working for one company go out of his way to help a rival, especially when he was not getting paid for his considerable trouble?