Because that's what batterers do. They want to further abuse and control the mother by securing custody.
Dad is identified as DWAYNE E. THOMAS.
http://www.pennlive.com/midstate/index.ssf/2013/07/angry_father_threatens_mother.html
Angry father threatens mother of his child after court custody hearing in Franklin County, police say
By Jeffrey A. Johnson
July 31, 2013 at 8:29 AM, updated July 31, 2013 at 8:40 AM
A Franklin County man who has a history of beating the mother of his son is accused of threatening the mother after the two participated in a court custody hearing Tuesday, according to Shippensburg police.
Dwayne E. Thomas, 21, of the 100 block of Mount Pleasant Road, Fayetteville, is facing charges of making terroristic threats and harassment.
Thomas allegedly sent threatening text messages to the mother of his child in which he said he was going to hurt her and damage her property, according to police. The texts were sent after a court custody hearing that
Thomas participated in by phone, police said.
Thomas on a previous occasion punched the mother of his child in the head at her place of employment, police said.