I don't know if it actually was her choice or her father's, but it seems to me that it's the right decision for him not to come to the wedding.
He's obviously not at all well and needs to recover from his heart attack. He is also obviously wildly in over his head with the media. I think Kensington Palace have something to answer for there as they should have taken him under their wing from the start and given him more help in dealing with press speculation. But the damage is done and now he has caused himself and his daughter a lot of heartache - that must be causing him stress, and I think he will be happier and more healthy for missing it.
I really feel for Meghan. She obviously had quite a complex and uneasy relationship with her dad. She must feel so betrayed that he went behind her back to have these press photographs taken, and it seems he is also texting gossip fodder directly to TMZ. While there are mitigating factors, he very clearly hasn't been putting his daughter's wellbeing first. If he had, she'd be able to have her dad at her wedding and now she can't.
I hope she still has a great day on Saturday, and that her father recovers, and that she's able to move on from this and have a reasonable relationship with him.