Honestly, despite all that he suffered through, I understand his willingness to do atleast this much.
My parents are now at that age where they need me and my brother to take care of them, even for everyday normal stuff, and even if our relationship with them wasn't the very best growing up, there is not enough hate in our hearts to ignore the suffering of two old people.
Maybe some people will think we're just naive or too forgiving, but I believe everyone should do what they feel it's for the best at the end of the day.
If Sei or anyone else in his position decided to ignore her, I would have understood that too, "you do you" because at the end of the road keeping score and bullshit like that amounts to nothing.