In this clip from that press conference, another reporter tries asking the same question, explaining that it's not a hypothetical question, but rather, a question of protocol.

To that, Bloomberg said, “We do not expect him to go down to the World Trade Center site. We don’t think for logistical reasons and security reasons the World Trade Center site can be visited by people who have come this year.” He went on to say Ahmadinejad’s visit would be “totally inappropriate.”