Locked Door and Shaka Zulu, apologies, RHS not S/O.
Of course it's self-interest. BALPA looks after its own, isn't that self-interest too? Just how many pilots are there out there who would sacrifice their own progress for someone else to benefit? Let's face it, if your company does well and you get promoted, you congratulate yourself on backing the right horse for a change. You don't agonize about the poor pilots elsewhere whose work your company has stolen.
That said, it needs to be a level playing field. BALPA effectively wanting to crew a new venture from within BA is not level, it's a cliff.
Shaka Zulu, my own company's T&C's couldn't slide any further, I can assure you. But if the Company was threatened by a whole bunch of Captains leaving to go to Lauren, the T&C's might actually improve.