The Daily Mail is a very opaque window on the world, so I am going to place very little reliance on what it chose to report. However I am a bit confused as to how these passengers came by this information?
If it necessary to use a forward hold only for baggage, because you cannot open the rear one, why would you tell the passengers that? I appreciate that if you need to redistribute passengers as a result, they need to be told something, but that should simply be confined to weight and balance issues. If it were a passenger door, then clearly there would be a safety issue, and the passengers must be briefed about the unserviceable exit and relocated accordingly. However for a cargo door, it is absolutely none of their concern, and nor should it be made one.
This seems to be a case of too much information, and not enough thought on the part of whoever chose to impart it.