Tonga is, basically, a third world country. Technology doesn't really exist far beyond the capital, and the island he was on was particularly remote. It really feels like the edge of the world, out there.
People, there, eat dogs.
So, while some may consider it poaching, a local in a place where white people are rare, may not have the same cultural view point about sea cucumbers which are huge and completely litter the floors of the shallows (I have seen them, myself, they are more than plentiful... they outnumber everything else) that we may have.
To him, they may seem a vast resource and far better to eat than dog.
Not only is Tonga the only place where you are still allowed to dive where the baby humpback whales are born, there is virtually no law enforcement. Some of the populace have zero interaction with any kind of official or tourism, and many of them in the remote islands live at subsistence level. They literally have no money and no way to obtain any.
Whatever the case, I figured I'd try to be a little informative. These aren't rhino poachers who make thousands of dollars a kill and leave the carcass to rot. These sea cucumbers aren't traveling abroad to land on the dinner platters of fancy, over-priced restaurants.
So, try to keep that in mind when "poacher" appears in the headline.