I think people are missing a major point, here. The issue isn't whether the guy initially looked wrong, the issue is that the guy ultimately acted wrong.
Refusing to leave the property is trespass; refusing to leave, when one is a large male, and the resident is a small female, can seem like something worse than trespass.
The AT&T rep was in the wrong for refusing to leave the property, period, end of story.
All you guys saying "no big deal" are full of it... if it had been your wife, and a large male refused to leave, I don't believe for an instant you would be so cavalier about it.