Kansas has been working on prohibiting the method of fanning, so we're very motivated to publish any incident, especially a local Kansas incident, with as much visibility as possible. It's a very hot topic at all our Hunter Education Instructor "orientations." It's not illegal, and many folks fall on either side of the aisle whether it should be or not.
Trespass is always a concern, and the overwhelming majority of the state is private property (continually hear KS is 98% privately held, 2% public owned land), but Kansas especially tries to be cognizant of implementing universal rules which apply to keep hunters safe on any property, public or otherwise.
To the commenters stating the guys shouldn't be shooting at "just a fan," take a closer look at what some of these guys use. I've seen guys use full body decoys as fanning decoys - and through binos in deep grass at 50yrds, it's very difficult to tell the difference. One guy I know even has a full body decoy modified to mount on his HAT, so when he's crawling on the stalk, he can be hands free (shotgunning, then he shoots prone). Another guy I know has a full body decoy which mounts on his shotgun or his bow stabilizer. I've fanned turkey's before, have used deer decoys before, and have even used those silly life sized cow silhouette stalking tools - I have to admit, it works incredibly well. I have a pro-hunter buddy which uses stalking decoy/silhouettes of cow elk and pronghorn in the same method as fanning and does extremely well each season... It all works, just have to be confident in who is around you, and have to be comfortable with the risk of trespasser shooting you.
I refrain from using the word "hunters" here, since trespassers are poachers and poachers aren't hunters, so I'll say it differently: If everyone taking a shot at game were diligent in their target identification, then fanning or other game-species stalking silhouettes wouldn't be an issue. Unfortunately, that's not the world we live in.