It seems to be an integrity thing for Jim. Presenting his work and then hear critics at an early stage might make him loose interest. - Why continue to work on something people don't like, and such. I don't know how open he is about input on the actual design of the aquarium either. With an artists approach to something (as I believe is how Jim works with these aquariums) I think it's almost "forbidden" to change your work to please others. (Not meaning fixing bugs, though.)
This is just my 2 cents...
(Sorry Jim for putting words in your mouth. I hope I'm not out into deep waters here.)