No, he shouldn't be outraged. The person wanted to dance with his wife, so he asked her. Since she's the one who would be dancing, it's up to her to decide if she wants to or not, not her husband's choice. If she wants to, she can ask her husband, "do you mind if I dance with him?" or something. But nowadays, I think the idea of having to ask the man to dance with his lady is very outdated and rarely done. And consider this -- how would his wife feel if every man asked her husband, "may I dance with your wife"? Won't that make her feel like a piece of property, that she's unable to make her own decisions? I think that has the potential to be a lot more offensive. Unless he considers his wife as a piece of property, no, he should not be upset at all. This is normal practice. All he has to do is observe what's going on around him to see this happens all the time.
And the two links posted by tango2x2 are certainly a good start. They're not fresh in my mind, but I have read them before and as I recall, they do a very good job at describing dance etiquette.