Talia was used to the superhuman life. She is one of the youngest superhumans alive and since she is also a part of the NSA she must be going on smaller-scale missions already, but that did not mean she could survive in the places that Mark goes to. Now that he got his powers back and many of the Anima knew that he was KING, Mark knows that stronger opponents were going to surface and challenge him. He did not know if it was okay to bring Talia into that sort of world when she was only this young.
Should he just harden his heart and send her away to live with Greg? Talia's life would not be bad with Greg and she would definitely grow with a loving father figure around her since Greg is also a father himself and she would be like other normal children. It's not like Mark lacked the money or time to take care of one more person, Mark didn't have any issues taking care of Talia. He just felt like her life would be easier away from him.
