The ending was unfortunate, but not surprising. The details about their existing businesses was troubling and I suspect the "due diligence" revealed more information that would make an investment too risky for Joe and Tim. Perhaps something about the partner who owns 49% of the business, or more debt. Since the details have not been disclosed, we can't determine if their decision not to invest was reasonable.
A lot of these show have the disclaimer that the investment is subject to due diligence. Perhaps doing this on the front end disqualify so many candidates, and the juicy drama that comes with them.
Jeremiah Bullfrog competed on Chopped as well. A lot of these shows are becoming crowded with serial reality show contestants.