Like said previously, this is RACING, and racing is, well, of course, racing. They have the blue flag for a reason in racing, BUT, go to a dirt track race and watch people follow that flag. It's just letting them know that leaders are on them, and they should watch what they do.
If they are racing somebody else and receive this flag, do not, in any means, expect them to move over or stop THEIR side by side race, because it's not going to happen. I know this. Haha..
It's understandable if you are the only one running in your area and the leaders are battling or are coming around behind each other. Then you can race but race clean. Once somebody gets pushy and starts hitting others, expect the same back, because once again, it's RACING. Racing is definately an emotional sport, and when you're caught up in an adrenaline rush, and somebody just runs you over, expect words to be exchanged. :P