He was an Episcopalian Priest. The altar is considered the "church" and to articulate this more clearly .. the priest and the couple were standing before God when they were at the altar. The only people who are to be at the altar when the ceremony begins, are the bride, groom and the Priest. The maid of honor, bridesmaids, best man and groomsmen are to stand to the side of the altar, facing the congregation when the ceremony begins. The bride and groom are to face away from the congregation, and to face the priest - the priest faces the congregation. Approaching the altar is not the same thing as standing at the altar. the father of the bride, approaches the altar, gives his daughter's hand to the groom, they then stand at the altar when the Priest instructs them to. This is a very, very sacred tradition .. one that is centuries old. the photographer was at the altar, behind the priest .. a very BIG no! no!
The Priest was well within his rights to suspend this ceremony. Those calling him an ass simply do not understand the tradition, or the symbolism of what the altar represents. They do not respect the authority of the Priest either.
I married in an Episcopalian church, however, I had a Baptist wedding ceremony. I am friends with Father Paul, the Episcopalian minister at the church I got married in, and my father is an ordained Baptist minister. Father Paul is also a Georgia State Trooper. My father conducted the ceremony .. and during rehearsal, very clear instructions and ground rules were discussed.
Having a father who is an ordained minister, I am thoroughly familiar with how weddings, funerals, baptisms, dedications and other religious ceremonies are officiated. Each denominational sect is different - Episcopalins have what they call "participatory" or "non-participatory" congregations. That is, in some churches, they allow the congregation to respond to the sermon, in others, they do not.
This Priest made the right call. You DO NOT EVER approach the altar when the ceremony begins ... not ever. And you definitely DO NOT STAND at the altar, like the photographer did. That is not only "rude' it is highly disrespectful.