One would presume the palm print (partial or otherwise) has been run through any available data base.

A negative result only eliminates the person who carried out the phsyical attack on Jodi.
It doesn't eliminate anyone who might be behind the attack or an accomplice who may have been at the scene.

This is why I'm interested in the fact that a cornseed dude is still a person of interest to the MCPD.

"Why don't you leave this guy alone. Some of these comments border on harassment."

Probably because cornseed dude was the last person to see Jodi alive, and his behavior after her disappearance was very odd, to say the very least.