Rule since 2009 has been DQ for any false start.
Pre-2003, every runner got a gimme of 1 false start, but they were DQed on their second, but it could potentially take ages to get a race started.
Between 2003 and 2009 a false start by any athlete meant the second, whoever committed it, was DQed, but that left room for tactical false starts.
Since 2009, it's been a straight DQ with no second chances. If someone had a false start and was still allowed to compete, then it sounds like the official messed up.