It seems like a valid question. We're also told that a black hole isn't visible, and we're told that this image is reconstructed from sensor data. Whether or not it's really fair to consider it a "photograph" of a black hole boils down to exactly how much artistic license is taken in reconstructing the sensor data. Not knowing how much of this is artistic license, I'm willing to take the scientists at their word, but to ask the question doesn't seem like a nitpick.

EDIT: In Dr Bouman's TED talk, she notes that there are an infinite number of ways the sensor data could be constructed into an image, and that they were looking for a construction that looks like what they expect things in our universe look like. So, there's some ambiguity in the definition of "photograph"