If people learn that they didn't wait in Standby then they will also know that they are waiting for a group that IS waiting in Standby. Otherwise, they would think, "Why are those G+ users waiting there?" Also, they'll see the obvious fact that they aren't cutting in front of them. Common sense says nobody cuts a line and then stops and waits for no reason. If they know they used the Return to Line option then they know about the Return to Line option. If they don't know about it then they have no reason to assume anything bad. If I'm backing g out of my driveway and my neighbor is driving g down the street and stops to let me out, I don't think, "What does that jerk think he's doing letting me go first?" You're stretching if you're trying to make this the negative scenario for this accommodation.