I like that article. It made sense in my brain. I think poly does have a lot more room for interpretation and negotiation than swinging does. To me, swinging seems more like an activity, like tennis or ice skating. It just happens to involve a lot of fucking.
In some ways, words are very arbitrary and sometimes even irrelevant. But in something complex, I feel the need to attempt to define at least my experience so I can narrate it to others in way they understand. Perhaps we should attempt to pay more attention to poly or swinging as how it plays out in our lives rather than finding a standardized cookie cutter definition.