I read the article as meaning that the gang was part of the cattle grazing/farming industry. They burn the land, they bring in grazers, and by the time anyone notices the grazers have "been there for a while" so it's difficult to remove them, destroy everything, and let forest regrow.
That said, I doubt removing one gang will make much difference unless they change the system that allows ranchers to stay on illegally burned land.
Yes, (replying to all here) you are correct. I found the claim distasteful to say the least, and reacted after reading the article. In any case, I couldn't have done a better job of pointing out the fallacy of it than the mongabay.com page. I would've edited again right away had I thought anyone needs more convincing of the overall point.
That said, I doubt removing one gang will make much difference unless they change the system that allows ranchers to stay on illegally burned land.