It's likely that at some point in your career you will have to interact with clients or present in front of an outside audience. What you wear and how you present yourself reflects on your company.
So, let me make sure I'm understanding what you're saying, here. You would reject a candidate for a software developer position (or any other mostly "back end" role) because that person may or may not some day end up making a presentation to people outside of the company?
Are you sure you don't want to take a bit of time and rethink that?
Are you sure you don't want to take a bit of time and rethink that?