I'm not having a 'pop' at the OP just trying to give some explanation of how BA would have dealt with this.
If there are several elites on the same flights then BA has to choose between them so some factor must have been in play. If there had been one less GGL on the flight he might have got the ticket
And if you look at my very first post you'll see I mentioned the possibility of EU261 compensation so I've actually helped him,