It's not clear to me from the information here that Sonos themselves can't refurbish a device that's been put into recycle mode. This seems to be a technique to block third party refurbishers only.
“Once your Sonos product has been deactivated, you can safely recycle it by bringing it to your local e-waste recycling center. You can also send your deactivated Sonos product back to us and we’ll handle the recycling.”