At the start of all of this, BA asked the crew for part-time volunteers and voluntary redundancy. Once they had the numbers they tried negotiating a plan. BASSA refused to negotiate sensibly, so BA had to impose. BASSA kicked up a fuss so BA had to start MF to cover the costs. All of this was threatened before hand, just as the removal of staff travel was. BASSA are still in dispute, so BA cannot go ahead with their plan of part-time for all who want it. BA would be in a right fix if BASSA were to win but all part-time requests had already been granted. However, BA can go ahead and grant the requests of those no longer in dispute. I think this decision makes logical straight-forward business sense.
The fact that it upsets the BASSA supporters who are being bypassed is probably pleasing to lots of people in BA. If you asked your child if it wanted some sweets, then you went in to the shop to buy it some and it punched you in the belly as you walked out the shop, would you still give it the sweets? Neither would I.