Like I said ... where do you get 'abandoned' (in the context of this discussion)? The OP clearly states that they were left on unused seats. Pax didn't abandon them, as there wasn't a pax in the seats. Airline didn't abandon them, as they were still in the aircraft.
Really? Interesting concept. The seats where the amenity kits lay were un-occupied. How do you assign ownership to a 'potential passenger'?
A whole new area of law??
Maybe I could walk off with those bottles of scotch in the lounge. After all, they are just sitting there, unclaimed and seemingly 'abandoned' by the lounge operator. Oh, and there's that iPhone on the table there. Its owner has walked off - obviously abandoned it. I may as well take it.
Bottom lone folks - if it isn't yours, and hasn't been given to you, or you have been given permission to take it, its not yours. Hands off.
Potential passenger,
forsooth.