Gunny has nailed it, which doesn't surprise me at all. Sometimes it's the departments, sometimes it's city councils, sometimes it's city attorney's offices, but somebody, somewhere in the policy-making chain worries about what will happen if a gun is sold by local LE and is later used in a crime. I don't know of anything in AR law that would bar them from being sold (once they no longer have evidentiary value), but if a gun can't be returned to its rightful owner, or if its owner used it in a crime, a court will often order a weapon destroyed.
As for me, I don't have a problem with Benchmade helping the local PD destroy weapons ordered destroyed. I don't own a Benchmade, and may never, but I'm not planning a boycott, either.