If Arnold had a problem with that, I bet the stuff established in the DS9R would have made his head explode, although that would of most of the recent post-series books.
Yep. Richard will always defend his actions as he was carrying out GR's wishes, but the Star Trek Office took a dislike to the tie-in writers inventing any new Trek lore, which stymies so many stories. I recall when RA first started doing conventions as a STO representative, there was the story of the convention flier which called their Guest of Honor, Diane Duane, "the creator of the Rihannsu". The flier turned up in the STO at Paramount and GR was livid. Not Diane Duane's fault, of course; she wasn't running around calling herself "the creator", and her reasoning in the novels was so she could give layers of meaning to the Romulus/Remus analogy set up by the show. This was around the same time as Paramount discovered that Franz Joseph had signed a contract that seeming gave him ownership of certain designs and concepts in the "Star Trek Technical Manual", allowing Joseph to license out the designs for "Star Fleet Battles", the roleplaying game (but then known as a "war game"), and Paramount was powerless to prevent Trek being taken in directions beyond GR's "vision".
RA's influence on the tie-ins' manuscripts ended when GR passed away, although he did go freelance as an advisor to other companies seeking to obtain licenses for Star Trek products. But yeah, I'm sure he'd have hated the open endings put onto DS9 and VOY as those TV series ended.