I generally agree with all you say.
However, as a college professor and a student of both suicide and homicide, I can say that cheerfulness is common in students who are suicidal. There's academic literature on this.
I think sending the money to the CIA or its subsidiaries is not the best lead.
I do think there's lots more known by LE and that this case is leading somewhere (although we may never know). I don't think it's drugs/gangs/cartels.
It is my opinion that there are far more persons skulking around college campuses than "random place in the US." I also think that the typical behavior of American college students leads to some vulnerabilities that attract such bad actors. Everyone knows that there's less active LE during the wee hours of the morning. That's when a variety of things go down.
There are likely viable leads - but perhaps too many of them. Every person in that apartment complex should be suspect, as well as all the nearby residents. It's a lot for LE to process. But what else is to be done? Unless Caleb actually told his roommates exactly where he was going after he returned the puppy to the apartment, it's pretty open-ended.
I could say a lot more about public messaging, but right now, the goal has to be to find the person or persons who made Caleb disappear.
IMO