I think she should say exactly what she said on the Disappeared video as you posted yesterday. Kim: "Phaedra and I were going over list of names of who she could possibly have gone to see ... and there's only that one person she would go do something for in the middle of the night and not tell anyone. Her ex-boyfriend, Steven Capobianco." That's her truth and she should speak it. IMHO.
In terms of MPD not focusing their attention on anyone else, if I understand typical police procedure, they attempt to clear people by examining their alibis. They were not able to clear SC. He had a motive, and by his own admission, was the last person to see Charli alive. Early on, he made a lot of statements to police that did not make sense to them. He called Charli to help him with his "stuck truck" and to talk. She stayed in her car the whole time, never once got out. The dog was with her when she was driving back to Haiku. He left his car, with its big tires, custom stereo, and broken rear window, on lonely, unpatrolled Hana Hwy near Keanae overnight Saturday and all day Sunday and it was untouched when he returned. It took him 5 or 10 minutes to fix his truck - loose battery cables. He wasn't thrilled to be having a child, he was warming up to having a child, if Charli was having his baby, he wanted to be in it's life.
If I were investigating the case and I had all of the information above, I don't think I'd be wasting my time looking for a serial killer.