He approached Obama. Obama did not approach him. In fact, it took some effort for him to get close enough to Obama to ask his question.

I'm sorry, but I just don't believe that if this guy had discussed the particulars of the business with his boss to the extent that he was making it look like he did (ie: an agreement that he was going to buy the business), the subject of gross and net would not have come up. Even if Joe himself hadn't brought it up, the owner of the business would have. And I also don't believe that Joe himself wouldn't have wanted to know how much the business made after expenses. Since Joe was saying that Obama's tax plan was going to hurt him after he bought that business, he knew that he was talking about profits after expenses.