According to articles I found, he didn't want to sign a contract with Major League Eating (the organization hosting the event) but went on the stage to compete anyhow. The police arrested him and charged him with trespassing and resisting arrest, despite the fact that MLE doesn't want him prosecuted.
I'm not sure why MLE not wanting him prosecuted should have any effect on him being prosecuted for resisting arrest, which has nothing to do with them.
I have no idea what he hoped to accomplish, either.