He’s moving soon
Just don’t do it. Why set yourself up for heartache? And let me tell you something, if you do date him for the few weeks or months he has left in your town, it will feel like the perfect relationship because it isn’t real. It’s like a vacation relationship: there’s an expiration date. So you aren’t even getting a real sense of what it would be like to be with him, then you’ll mourn the loss of him.