Maybe that's just the general gear he has? When I travel or generally go anywhere the gear I take totals around the 5 grand mark, sometimes it doesn't even leave the camera bag but I always have it with me. If I were going to a wedding or similar event and was taking a camera (for whatever reason) that would be what I took purely because it's just my default gear, nothing whatsoever to do with proving a point to others by having a big posh camera and if others took it that way the problem would be theirs, not mine.
I've shot a couple of weddings only for friends and family, I'm certainly not a wedding photographer by any stretch of the imagination but surely this just comes down to simple 2 way respect? You're there as a guest so you respect the fact the paid guy has a job to do and you stay out of his way (which by the sound of it is exactly what the OP did), and as the paid guy you accept that you're a hired part of someone else's special day and that day is special to more than just the bride and groom. It's special for the guests as well and if they want to record the day they should be left alone to do so.
If a guest is genuinely getting in the way of the pro guy then I don't see anything at all wrong with politely mentioning there are certain shots he needs to get without having any distractions, but to just randomly have a go at a guest who isn't in any way causing a problem is just plain disrespectful and arrogant.
Probably is his general gear, I didn't think anything different, I just wonder why you'd bring it to a wedding. I go to weddings all the time, and I don't even bring a P&S. For several reasons:
1. There's a professional there.
2. I don't want to be *that* guy with the giant camera. (though that's just a personal thing, I'm not holding anyone to my standards in that respect)
And three lenses? It doesn't sound like a situation where he simply only had that gear, it sounds like he made a decision about the best equipment for the task. I just dont see the scenario playing out where he's faced with the dilemma of simply HAVING to photograph the weddings, but *bugger*, he's only got a Canon 5D3 and three lenses! Guess he'll just have to bring them all in his Lowepro camera bag!
My argument here is that there is a professional photographer in the building. They are there to do a job, and if you are there in the sidelines with your giant camera and three lenses, the chances are that sometimes, that camera is going to steal focus and potentially ruin a shot. It's also going to steal the photographer's focus, because he'll always have a second eye on you wondering if you're going to be an idiot. Also, this is one version of events. OP says he wasn't in the way, but apparently, this other gut felt the need to walk a considerable distance to tell him to bac off? Sounds fishy.
The OP is just one person with one experience, the wedding photographer was just one person with probably 50+ experiences of guests with giant cameras acting like the backup shooter and generally ****ing him off.
I've shot 5 weddings in my life, and while I will always remember them as the most inane, mind-numbingly tedious jobs I ever shot, I will also remember the intensity of the responsibility and the pressure I felt to give two people one shot at a great visual memory. I can remember the tension I felt when people pulled out DSLR's during proceedings. You never know what kind of camera person they are.
I mean, Jesus, think about some of the people on this forum - can you imagine them at a wedding? Judging you as you work, questioning you about your gear, describing your technique to other people, remarking on which camera settings you are probably, or should be using, which lens is appropriate.. Ugh, it's enough to irritate me even now.
Not saying the OP was that guy, but he's on this forum, which means there's a chance.
Photographer handled it like a *****, but I don't blame him one bit.