Whether the people applying to Open Lies are to be referred to as "scabs" is not especially relevant. The fact is that they are in contravention of the IFALPA recruitment ban which means that if they ever need the support of a union (and BA have already said they will recognise BALPA as now), they will find themselves on their own.
As someone who currently works for BA, that is not a position I'd feel particularly safe in considering some of the individuals who are running the show. Don't ever, ever, ever put the slightest foot wrong and you'll be absolutely fine. If you screw up, God help you because it's unlikely anyone else will.