Not understanding your logic here? (Not intended to sound obtuse.) You're saying that if someone carries their own headset, then leaves the aircraft without plugging-in the company headset they're a DB? How is said person who leaves the aircraft, assuming the next person to get on the aircraft has their own too, a DB?

For reference: I carry my own Telex 850. (717) I have never once plugged the company headset back in, thinking the next person may have their own too. (Guess that makes me a DB?) I choose to think of it as:
1) Saving the other person time, if they have their own headset, OR
2) Not being that big of a gawd dam deal if they don't. The Co. headset is easily accessible and takes maybe an additional five seconds to connect.

Good day.