the answer is patent protection. The marketed products (humalog in this case) are patent protected and can't be used in a U.S. trial w/o permission. doing the trial in australia gets around the patent issue.
By the way, the trial really couldn't have gone any better for BIOD. The results were very good. Maybe Ely Lilly will be interested in a partnership now- humalog comes off patent soon and they need to keep the cash cow going. I think the stock is a strong buy and think today's move will continue for some time as people digest the impact of these results.