You do still have to describe a mechanism by which welcome mats are about chicken beheadings. Somewhere back along that line of mechanism there has to be an intentional act on the part of a human being - it may be an act of interpretation or it may be some other act, but somewhere there has to be an intention, otherwise you can't say the mats are 'about' chicken beheadings, there is just some coincidence involving chicken beheadings. Of course, the mere act of you having discovered that there is that coincidence may be sufficient intentional interpretation that you can make the claim.

There is also the fact that most people lose interest in a discourse if intent is not obvious and near the surface, since intent is the only thing they have any control over. People like control.