yes, I bet he was in a place he knew he might be seen and have a photo taken, just like that photo of Brad Pitt that has been on the internet for years.
I bet a lot of celebs would like to show off, but seems most big names don't because it might affect their career. He probably likes the idea that thousands or people want to see his cock, no matter how big it is.. I know if I were him that thought would drive me wild..!
BTW, even though he looks smallish to average in that pic, he's damn hot! I'd definitely suck him til he came and chug his sperm.