Mr M.
Does this not show a certain lack of intent to return to her job in any meaningful sense?
No, it shows a wish to have her children close together. Nowhere to my knowledge is it written that you cannot do this simply because you are a pilot. Plenty of female pilots have had two or more children close together and thus have taken a large amount of time off and have come back at 50%. This is not a new phenomenon. What is new in Jessica's case is that Jessica's (and two other females who applied for 50% at the same time) application was denied on resource grounds when the department had made zero budget for Airbus P2s 50%. Then the safety argument arose half-way through. It was never considered at the time of the application nor at at the appeal.
As for the question of standards after time off, Jessica successfully completed her return course in 15 days to the high and exacting standards required by BA. The phrase 'cleared for line flying' is a powerful one and means one thing - you are good enough. The same phrase would apply if you had been off long term sick for up to 18 months and returned to flying. BA training has its standards. They are very high, and they will not release anyone on to the line unless they are satisfied that the pilot is capable of doing the job, regardless of how much time they have had off. Incidentally, there then follows a period of 2 months' full-time consolidation before the PT flying commences.
As for your query about when a female is grounded, in BA they are grounded as soon as they declare themselves to be pregnant.
Hope this helps
Dave