Looking at the Japanese transcript using Google Translate, I've found the mention of the 2 million... and I'm pretty sure it's not talking about profitability of games in general.
Rather, it's talking about the difference between games just for Japan and games for the whole world. It's saying that 300,000 units are what you can expect as "average" for games released in Japan only, and 2 million on average for worldwide releases.
Pretty sure it's less about "how much do we need to be profitable", and more "how many can we estimate when working out how much to spend on a game". In other words, if they're taking a risk if their game needs more than 2 million and it's releasing worldwide.
To put it another way, it's not "the average Nintendo game needs 2 million to be profitable", but "the average Nintendo game sells 2 million".
