I have anxiety problems and sometimes in missing child cases where they analyze the parents behavior, I wonder how badly I would look to the GP if I was in the same situation. I am not saying I would care what others thought, but I'm sure I would be picked apart pretty badly. I would be scared of a poly also for the same reasons and the fact that I don't know much about them.
I have yet to follow a case where a parent turned out to be guilty but they were suspected in the beginning before the case was resolved. I do know that every parents behavior that I witnessed was different and unique to that individual.
MR being the last to be seen with Dylan and (some) of the other things that have been observed are enough for me to consider him suspect, but not enough to convince me 100% that he is guilty or prevent me from considering other possibilities. What other people say is not going to convince me of his guilt either, unless it comes from LE or MR confesses.
That's just me and how my brain works.