Either that, but if sexual impulse issues, control issues, personal boundary issues, with a possible history of prying on vulnerable impressionable females to get near their children, it could be possible that if the other proclivities hadn't yet pushed his family apart, besides Julia, that news of an affair/s with other women may have? Considering he did clean in the Ypsilanti area, it may be possible Julia ran into him at the wrong place at the wrong time, and he knew and was afraid of her saying something or having some physical evidence thus the disarray in the room? She may have known and had no intention to tell too, and the "Trust no one" text may have been about his attempts to fish for information around her and her reaction.
If Julia was taking action over child *advertiser censored* or whatever else and Turnquist was in any way threatened by this or knew or suspected, then his motive may have only been self-preservation, thus no full statement that would make all this go away, it seems. He may not have ever cared more for his children than himself. What would prompt Julia to take action though? I imagine it would involve support from an other or others along the way, it seems possible. She was a girl who took big strides in a short time.