I'm disturbed by all these answers. Everyone seems to be supporting the candidate, arguing for giving the guy a chance. Why should an employer do that?
As an interviewer, your responsibility is not to be a nice guy and give a guy a break; it's to protect and promote your employer's interests. If you can do so in good conscience and give a guy a break, that's great, but first and foremost is to maximize your employer's assets and reduce your employer's risks... and hiring an employee is one of the highest-risk activities a company will regularly do.
Between two equally qualified candidates, one whom you have knowledge of previously (potentially) demonstrating thoughtless, disrespectful, and/ or unprofessional behavior, and one who you have no such knowledge of, a responsible interviewer will favor the employee with no historical "demerits". This isn't a trial by jury either; you're not responsible for determining "guilt"... just risk.
Whether or not you interview him is, of course, your choice... but if you feel that it represented a behavior that you would not want to deal with at your current place of work, of course that should be taken into consideration, and if you feel that disqualifies them... then they should be disqualified, because your employer respects your opinion, and has not only hired you, but wants your input on this candidate.
There are lots of candidates out there, and there are lots of positions out there. There are lots of reasons why not everyone gets hired for a job they apply for. Maybe he was having a bad day, maybe a calendar invite got lost in the mail. Maybe it totally wasn't his fault. It's not your responsibility to figure that out. You go with the information you have, and if it hurts his prospects for this position at this company, there's certainly lots of other employers that do not have that information, and may hire him (and likely will be happy with him). You don't need to feel guilty about it, and you don't need to justify it.