Oh boy, let's see.
1) LE's belief in the credibility of the MFH plot. Wackos come out of the woodwork in cases like this, and LE has to sift through tons of bs, so if they thought this was credible enough to warn KH, that says something to me.
2) The timing. If a stranger was planning this, it's pretty gutsy to stroll right into a school on any day, let alone a day when there are probably more parents milling about than usual. Most stranger abductions that I recall are crimes of opportunity, a kid walking home from school alone, out in the front yard alone, etc. On the other hand, for someone like TH, she might have thought this was a better day to plan, no one would give a second thought seeing her at the school or leaving. Any other day and Kyron's absence would have been noticed much sooner.
3) Motive. A stranger motive is obvious. But other than a stranger, who would possibly have had a motive? If there was a MFH plot, she obviously has a serious hatred of KH and serious psych issues as well.
4) Behavior. The sexting thing - seriously? That is Scott Peterson with Amber after Laci died. That's CA partying after Caylee went missing. What mom/stepmom could be thinking about trying to land another man at a time like this? What mom/stepmom wouldn't be consumed with worry, putting 100% of her thoughts and efforts toward that sweet little boy?
5) Statistics. Statistically, children are more likely to be abducted/victimized by family than strangers. Naturally, that's why LE turns the focus on the family first. They will also look at the last person to have been in contact with the missing individual. With the exception of his classmate, who I'm pretty sure had neither the desire or capability to harm KH, we're back to TH again.
6) The custody issue. I'm guessing OR is similar to other states in regards to temporary protection orders (TPO's). A request is made before a judge that a child is in imminent danger if protection is not granted. Judges don't toss these out like candy. Still, after some period of time, in my state it's ten days a hearing must be held to give the party reason to contest the TPO. I think the reason her atty's did not contest it, is that it would have opened the door for the MFH guy to testify against her and she would have been open to questioning about both that and Kyron. If that's my baby, and I'm innocent, I say throw all the questions you want at me. No way am I not seeing my baby for a year. But she can't do that because I think she's in total self preservation mode, IMO.