If you read through the various posts and threads on this topic, the problem reveals itself - there is no 'official' reference point.
Everyone wants to impose their view of what blue flag means, based on
either their favorite form of racing, their team views, the views of the 20
people they frequently race against - whatever.
Maybe the dev's should take the responsibility of presenting an
"on line racing guide" as part of the game. Through whatever means-
a splash screen, a tab, a readme file. Sure they can be ignored, but they could at least be referenced.
If you were racing on a server, it would not be so much a matter of interpretation anymore, there would be a reference to point an offending
driver to, and you could say 'this is what we expect in these situations'.
Whatever is included, and however it is concluded ( consensus, using
a specific set of rules from the rule world) isn't the relevant issue at the moment. Since it is a game, or sim if you prefer, the rules don't necessarily have to be strictly from the real world, just as driving the sim
isn't strictly the same as the real world.
What I'm suggesting is simply a common reference point, not that the dev's dictate what can and can't be done. The forum is not the place to
decree what is and isn't proper behavior, as a vast majority of people
don't view it. The same with a given team website or server.
There is only one way to be certain that everyone who plays the game
is on the same page, and that's via the game itself.