The worst case I've ever experienced was at our own Cedar Point. (The following information is given for factual reference only, and it does come full-circle in the end. I'm the farthest thing from a racist you could find.) A group of friends and I were in line for Mantis (which, as you all know, moves at a snail's pace anyway. One young African American kid excused himself through the line, claiming he had friends up ahead. He then stopped between two groups that did not recognize him and stood by himself. Within minutes, a group of a half-dozen rather large, rather intimidating African American men did the same, passing by everyone in line to "reunite" with their friend who had cut a few moments before. This all happened in line behind us, so we were still ahead of this group.
In other words, the group had sent forward a "scout" to get as far as he could in line without anyone saying something, and then they simply said "Oh, we're with him" and made their way towards the front. I'm sure they skipped at least twenty minutes of wait time.
My dramatic, high school friend who always says what everyone else is thinking (you know the type) waited for the ride and, upon entering the station, told the person with the height stick. He directed us towards the ride operator, who directed us to the ride supervisor. She listened to our story, sunglasses over her eyes, a stern look on her face. She had us point out the group, who was just making it up the stairs to the station by time we were talking to her. She thanked us.
We waited at the exit and watched as they walked away, having enjoyed their virtually wait-free ride at everyone else's expense, laughing and hollering about how short the line was. We saw them again a few hours later.
Basically, it was frustrating. If my group of friends had done it, and the supervisor had been alerted, we would have gotten our just desserts. But no one (including any security guards?) saw fit to approach this group of intimidating African American men simply because they might've actually had to step outside their comfort zone (which is yelling at scrawny caucasian "punks" who are afraid of them). There was a double standard that day, because it was simply "easier" to let it slide. But I can guarantee that if a group like my own had tried the same stunt, we would've gotten much worse.
If I'm understanding you correctly, then there isn't really anything the ride op could have done. In order to kick someone out of line for line jumping there need to be two groups complaining. I will usually give a general ''line jumping is not tolerated'' line to the people that were accused if there was only one person or group accusing them.