This late in the season that group was probably forced to go to Smith. While rude, this tactic is pretty common, and happens more frequently than anybody is prepared for. WA has a law limiting group size, but many seem to ignore it anyway. It sucks that this happened to you. My guess is "Spiderman" from your post. You could have potentially done the variation start, and beat at least some of them to the first station. Or pushed a little harder and maybe tried "Trezlar" or "Zebra Zion", both popular climbs also. That small bump in grade seems to weed out many of the total gumbies, meaning if you do have to wait, you might not have to wait as long. I personally am pretty sick of this ethic, having arrived early many times to find some group has completely taken over. My personal pet peeve is with single pitch stuff, when they show up at the crack of dawn and string ropes on everything at the wall without leading any of it, then sit back and have a picnic teaching how to put on harnesses etc. Acting like they own these routes if asked for a quick run of 2 people.
In this situation it's always acceptable to ask to go first, but in my experience it's almost never granted.
That park is big, with many options. Next time head up to the Marsupials...