Did they move when they saw you come up? If you were the only person to come up on them as they were taking photos (no matter how retarded you thought those photos were), and they got out of your way, then I really don't see the issue. If they had said "Fawk you.....you'll wait until we're done with photos"....then yes, an issue.
Sounds like they were enjoying their day, and got out of your way so you could proceed on your way to enjoy your day.....and you were pissed about them doing so. Self admittedly pissed because you got lost and wanted to catch up with your buds. And by their being there, they irritated you by their very presence.
Doesn't make a lot of sense. Unless stock rigs shouldn't have been there in the first place.
Is that it?
If the group did not let you by in a time frame you found acceptable (however that is defined) and it was a Nissan event I was a part of then, I apologize for their mis-step.
If it's just that you didn't think they should have been there, in spite of getting out your way so you could proceed.....not so much.