You make a good point remoak. If I may continue your reasoning so much of what goes on in aviation is based on seniority, some times directly, and sometimes with seniority being used as the 'tie-breaker' in a decision or situation involving 2 otherwise equal pilots. This decision by BMI Baby rides roughshod over all of that, and casts doubt on how future decisions may be made.
As I understood the legality of LIFO, and seniority lists as long as the list is based solely on date of joining the organisation, and has no factorisation based on age, race, etc then the LIFO list can legally be used. This is the case at BMI, and BMI Baby whereby one joined the list at the bottom on joining the BMI group with no credit for age, rank or previous experience. This was the basis of the argument as promoted by the BALPA CC. BMI Baby damagement wanted to firstly target the redundancies to the base where aeroplanes where to be withdrawn from, Birmingham, and the added a penalty factor for any disciplinaries that individuals may have.
The BALPA CC proposed several other measures to firstly preserve jobs, and secondly to preserve the credence of the seniority list (both within the company, and for the industry as a whole), but the damagement opted to impose their own decision, and ceased negotiation with the CC.