If it shows that too many people abuse the system Blizz could still give locked roles a try later on. I just think we should start out with an open approach and hope for the best. Because, again, sometimes you really wish to have 3 tanks or 3 DPS. Admittedly one more often than the other.
Fake reports are a thing either way. Even outside of Role Queue players are getting reported for things they didnt actually do. And as far as I can tell this doesnt seem to be much of a problem because for reports to have an impact there needs to be a considerable ammount of them. So if an innocent players is getting fake reported for allegedly picking the wrong role its probably not gonna have any consquence. But players who consistently abuse the system will rack up those reports in no time and end up with due punishment.