It was- and this issue was brought up earlier in the thread:

Quote Originally Posted by arguskos View Post
You are aware that a good number of these creatures have been printed by WotC, including the Flind (who are awesome, btw), right?
Quote Originally Posted by Rappy View Post
Correct, they have. Necromancer Games got specific permission to utilize them for the Tome of Horrors; otherwise, they'd be in so much hot water I doubt even their bones would be left...
The Aurumvorax, for example, was in the Expedition to the Ruins of Greyhawk 3.5 ed WoTC adventure.