why should it be legal to abort them, when it isn't legal to abort babies who will be born healthy
WP, it's not so simple. Look at some figures - 40-50% of them have congenital heart disease, 60-80% have hearing problems, and they need constant help and support throughout their lives - something that isn't offered in Poland. They aren't born healthy, and they're not capable of living truly independent lives - so they effectively are a burden on the parents as the state simply doesn't provide for them, and society is largely unwilling to help them. They can rarely find ordinary jobs, and they also suffer from the onset of dementia much earlier than the rest of the population.
It's easy to be against it when you don't have a family, but imagine if you have one kid, and the second could have Down's syndrome. Would you be willing to sacrifice a lot for the older kid for the sake of the younger disabled one? Imagine having to tell your healthy older kid that he can't have many things because you need money for treatment/rehabilitation of the younger one as the society/government won't pay for it? Imagine knowing that if something happens to you and you can't work, the disabled child will receive almost no support from the government and you'll still have to look after them?
I think it's looked at from a moral standpoint.
Nah, it's all about the Church support. The bishops have turned a blind eye to the things that PiS have been doing, but now they want something in return. It's really a bad situation for them - I imagine they'd be very happy for it to be kicked to the sidelines and ignored, but they can't ignore the voice of the bishops, especially when the threat is clear.
But as I said earlier, I don't think the law will pass. The Church has no real option - if they stop supporting PiS, what other alternative is there for them?