The father didn’t “lose” anyone. His daughter is still right there, he could have a loving and close relationship with her if he chose to accept her for who she is. He didn’t lose his son, he chose to reject his daughter.
Choosing to not support your children is how you become estranged from your children, not something to feel sorry for the parent for. It just makes the father a piece of shit. This statement is true of all shitty parents, not just transphobic shitbags.
https://genderdysphoria.fyi is a good resource.