From what I’ve read on this, the mother with the pram had a (temporary) disability due to injury and had booked ahead to get assistance and that space had been reserved for her. Because she was injured she could not hold her baby or remove her baby from the pram and had made arrangements with the train company to facilitate that.
When she arrived the scooter was in her booked space. There were other places that the scooter could have been kept allowing both the woman with the scooter and the injured mother to travel, but the woman with the scooter refused to move it which meant the injured mother would have had to get off the train and not travel at all even though it was possible for both women to travel safely if the scooter was removed.
I travel regularly with two disabled people and it is true that accessibility for disabled people is very poor on public transport.
But the biggest problem we have when travelling is frequently other disabled people who don’t make advance arrangements but turn up at the station and misappropriate the assistance we have booked even though they are frequently able to cope with less assistance than the disabled people I travel with need. A number of times we’ve been left on the platform watching our train pull away because someone with a scooter has diverted our booked help to themselves and left us in a situation where it is impossible for us to board. We usually travel from an area with a large elderly population so it does happen frequently.
Although I do agree that disability accessibility does leave a lot to be desired, I know from bitter experience that frequently other people with disabilities can behave quite badly when it comes to consideration for other people who have disabilities and are more entitled because they planned ahead and booked. I suspect that is probably the situation here too.