I want to add a "locals" perspective for folks who have never lived in tourist areas where armies of visitors appear at certain times of the year and take over the countryside or shoreline or whatever, often with no regard for the environment or the people who live there full time.
Who knows, there could be something more than meets the eye to what is happening in this picture. This guy could be a local who doesn't want you to be happy and wishes, that, as a group, everyone left and never came back.
Maybe he was unapologetic because he did it on purpose to drive off the elks and the photographers. Photobombing your shots and producing images of panicked animals fleeing the scene as quickly as possible may be exactly what he had in mind.
I've lived various, sometimes remote places, that attract large numbers of seasonal tourists. Most locals who did not profit from tourism, wished that the tourists stayed in Chicago or LA or NYC or sometimes whatever city in the lower 48 that they come from, would go home and never come back. Sometimes locals who wish tourists never took over their countryside take action and do this kind of thing on purpose to get the point across that they don't want tourists in their community.
In the fishing world they move their boats in front of other boats right where people are casting and anchor and turn up the music and party. Sometimes they waterski around boats to drive away all the fish and toss the people fishing around with the wake of the ski boat. Jet skis speeding around in circles driving off fish and wildlife is pretty common since those annoying things have been invented. Sometimes it's because the operators are clueless, other times it by intent. Get out of my fishing spot, tourist!
In the hunting world people urinate and leave cigarette butts around hunting blinds or the bait so that the deer or whatever won't come near them. Sometimes it's amateur hunters who don't realize that animal's sense of smell is their strongest sense and other times it local sending the message "go home, we don't want you here". On opening day nonhunter locals sometimes randomly fire their weapons or set off fireworks at sunup to drive the deer or whatever into hiding.
There seem to be many examples posted in messages here of behavior with the sole purpose of sending the same message to photographers who flock to areas like the elk farm preserve in Pennsylvania or Rocky Mountain areas to recreate Ansel Adams most famous shots with a few thousand of their closest friends.
I'm not condoning any of it. The point is that the next time someone pulls up and parks their car directly in front of a group of tripods all pointed in the same direction it may not be an accidental social faux pau. Someone seemingly intentionally driving off the critters you are trying to photograph might be exactly what they had in mind when they entered the water, as in this case. They may be figuratively giving you the finger.
It maybe because they have to pick up mounds trash left by tourists every season after they go home. Maybe it's the congested traffic tourists bring to the paradise countryside's that are their homes or wilderness trampled by mobs. Or maybe they are tired of visitors leaving designated public areas and trespassing on private property.
Expecting cooperative behavior from people sending the message that they do not want you there just isn't ever going to work. And as is pretty noticeable from many of the remarks here and the original image, lots of tourists also wish that certain other tourists went home and never came back.