^^ Which thought? That Andrew Probert's genuine Enterprise-C
does not belong to the Ambassador Class or that ILM may have assumed erroneously that they were doing pre-production work for a prequel?
The problem: The whole "Tauntaun lizard" thing had been abundantly illustrated in Ralph McQuarrie's pre-production work, hadn't escaped the watchful eyes of fans, and required an inevitable and honest answer.
IIRC the possibility that ILM did pre-production work assuming ST III would be a prequel, is a conjectural theory. Should it turn out to be correct, it would reveal a serious lack of communication (and professionalism) between Paramount Pictures and ILM at the expense of those responsible. Not necessarily the kind of stuff you want to publish, but after 30 years maybe those involved could look back and consider the miscommunication to be an anecdote worth telling (and I'd be listening with interest, of course