JMHO:
E-mail from Mr. Horman suggests this family has had plenty of access to legal counsel since early on in this case - through Intel, and otherwise. The've been told not to talk to media, no doubt about that.
Here's what I see: A couple going somewhere familiar together during crisis - to do something constructive to relieve anxiety and doing it together - a place where they know people they feel they can trust - a place where they can just go together, support each other and not be harrassed. (their gym)
Then I see them trying to get home and realizing their lawyers were probably absolutely right about not talking to media. (Thinking advice is: don't talk to media - just like in Mr. H's e-mail)) If you don't talk to media, they won't follow you so much.
I think there's nothing unusual with this victim's family or this couple except they are smart, they have resources, they are using them (see e-mail) and they are choosing at this critical time to be private.
IMO, those who want to take the victim's parent's private and joint visit to their gym and make it into something sinister are missing all the obvious signs with regard to this case. It's a criminal investigation into a missing/endangered child. Foul play, not accident. Likely abduction, and not mom/dad violence.
If anyone wants to discuss that that this family is disengaged from their child's disappearance and has not, in fact, been using every resource available to them, providing every photo and video and every bit of information they can, providing clothing for dogs, visiting search sights and fully cooperating with everything LE/FBI requests of them, here at WS, please remember that you need to provide the link that indicates this is a fact.
Otherwise such conversation is wild and unfounded speculation about the behavior of the victim's family, and that's completely out of line. IMO.
By the way, Horman's dad is an engineer. I have personal experience with a variety of engineers, having gone to college, lived with, and work with engineers. Engineers make lists, prioritize, keep balance, and do the things on their list in the order they need to be done. The can be rigid in annoying ways, but also in endearing and dependable ways. Including their rules about getting exercise, if that is part of their regular routine. I have seen 70 year old engineers make lists about "how to grieve properly". They are fact-based scientific creatures. They get comfort from order, logic and process. I think there's lots of folks here who know engineers, and even engineers will smile and admit yes, process and routine is comforting.
I think it's extremely important to respect the fact that everyone's different and not immediately assume that the way someone is handling their grief is a sign of guilt. I think it's part of being a decent human being to hear LE saying "the family has been completely and fully cooperative" and realize that that likely means the family has been completely and fully cooperative.
One additional observation:
I noted SM's FB went private within 24 hours of bloggers rushing to point fingers at SM's workout shout-out to her gym friends, and the fact that there is a white truck next to her red car, as proof she's capable of doing sinister things to her son. There's a support team in place watching and supporting this family's privacy. Frankly, I'm glad to see this family has this level of intelligent and thoughtful support. And that feeling comes from watching many other cases develop here on WS with very different family dynamics.