Greentooth is free and open as far as I know. The actual polycount logo is trademarked. Thats the logo with the word "polycount" not greentooth. So companies don't have to worry about polycount coming after them and artists aren't putting their companies at risk by using it. Now if they started using the polycount (text)…
Good job guys. We're not a secret anymore. Pack it up, we're done! https://www.polygon.com/2019/6/18/18683651/polycount-logo-overwatch-spider-man-easter-egg
Also our Terms of Service, at the bottom of every page, explains how the Polycount logos are trademarked. Greentooth usage is governed by what's on the wiki. And we make an extra effort to accommodate requests from game makers if they need clarity or waivers. We love seeing the Greentooth in our/your games!