Looks Like I Bought A Book With Stolen Art

I don't know for sure yet, but according to THIS thread on RPG.net, it looks like the PDF of the unofficial 6th Edition Tunnels and Trolls rulebook that I purchased from DriveThruRPG used a piece of art without the authorization of the artist.Not only that, it looks like James Shipman and Outlaw Press have done this multiple times with other products. If this is true, this sucks and I am sorry