How do you know your sisters abortion experience isn’t coloring her world view? Maybe she genuinely feels bad about it and thus doesn’t want her daughter to feel how she feels? Maybe she became pro life and posts those things on Facebook because she genuinely feels bad about her abortion and regrets it and wishes she made a different choice?
It might be deeper than just someone being a hypocrite. Seems like maybe your sister was traumatized by her experience in some way.
Everyone tries to make it seem like abortion is just a medical procedure, but it affects everyone differently. Some people don’t care at all, others are traumatized. Not a political statement, just being real about it.