I believe that David relapsed. I don't think that he left home on Saturday, August 5, 2017 at 8:30 a.m. intending to "binge" on drugs/alcohol for the weekend. Unfortunately, I believe that the company he kept in Maryland that weekend made the temptation too great and he succumbed. If he had been clean and not using (drug naive), a sudden drug overdose is very likely upon resuming drug use. One of the individuals is associated with criminal drug distribution charges in her past. I believe that David obtained the drug that killed him while he was visiting these two individuals in Maryland. This is just my own personal opinion.
LE is in a very tough position. On the one hand, this missing person (David) has sealed his fate by making his own choices. I can see why LE has a jaded view in this type of situation. There would be less crime if we had fewer drug users. But, on the other hand, the reason that LE exists is because we do have crime -- no matter what the cause might be. In drug-involved cases, they are not as committed to getting to the bottom of what happened to someone who went "missing." I can certainly understand their viewpoint. I am frustrated, and I am only a spectator.
This case reminds me of the case of the missing Chase Massner (since found deceased) -- for which there is a thread here on our revered Websleuths Site. The last known individual to see Chase, Brad Clement (arrested and now in jail awaiting trial in Chase's case), was "oh so helpful" in cooperating with law enforcement, media, family members, etc. However, ultimately, the "missing" Chase Massner was found buried under the deck of the residence owned by Brad Clement at the time of Chase's disappearance and where Chase was last known to have been seen. Even still, it cannot be proven that Clement was responsible for Chase's death, because cause of death could not be determined. Yet, in the absence of an admission of guilt, countless resources will have been expended in taking this case to trial to seek justice. The end result will fall short, in my opinion.
There was help, I'm sure, in concealing David's body. David was 6'4" and 230 lbs. Probable cause needs to be established. Otherwise, nothing will come of David's disappearance. It is probably too late for CCTV footage. So the story of the woman who had access to David's car, after he went missing, who initially claimed that she did not drive the vehicle but later admitted that she drove it to a convenience store to get cigarettes (after David "went missing"), probably cannot be corroborated fully. The information that I have had access to has come from listening to the podcasts referenced very recently on this thread. The information provided has led to my sad conclusion that David is deceased from a drug overdose.
All of this is just my opinion.