Property rights can be defined in a lot of different, somewhat arbitrary ways, so I think a deeper explanation for why something is bad is sometimes needed than

Property rights can be defined in a lot of different, somewhat arbitrary ways, so I think a deeper explanation for why something is bad is sometimes needed than just "it's theft". If the exclusive right to the cardboard was taken away from the people who currently claim it, then it wouldn't be theft. Would that make it ok?