I was reading the book with the transport today and saw on page 6 that the GR-75 can be used in place of your asteroids you place at the start of the game. Is this going to be tournament legal?

Generally no. I can't find the reference for it right now (I'll keep looking), but if I recall correctly it is expressly forbidden to be used as such in Premier tournaments but it may be legal in other tournaments if it is stated so well ahead of time in the tournament announcements. Expect it to be illegal for use unless you read otherwise.

Which sucks a big one.

I was kind of hoping we could use it as terrain instead of those boring asteroids.

Think about it , after you flip the ships base to blank Starfield it really isn't a ship, but just another table decoration.

Oh well rules is rules.