you are right, it is unfair to ask the last year candidates who made it through to start from zero and go through the selection again.
The decision which was made to empower BDB to take care of the selection is simply becuase the program is no longer Gulf Air's, BDB is paying for the training of the candidates and the selection process should be entirly theirs. GF offered to facilitate the selection and the placement on the course etc, but with the recent misconduct the decision was made to remove the "control" from GF.
I heard that the candidates who'll complete the training might also be employed with national airlines other than GF, such as Ajwaa, royal airline etc.