My thinking is, he knew he had to act incredibly fast in order to get on the run. I get the impression BL is very cerebral - he knew because he and GP were traveling in a remote area with little reception he had SOME time before she'd be found but was unsure about how much time. Also, he seems incredibly manipulative. I believe he raced home, all the while planning a believable story to tell his parents about Gabby (which is why neighbors said everything seemed fine, they went bike riding, camping, etc., his parents believed everything was fine at the point in time), to buy himself time before they were aware of the grave circumstances... in that window of opportunity he went for a hike at the reserve, when really he went on the run. That $1000 dollars he fraudulently spent? Likely a items to help him while on the run, he stowed this cache of gear prior to returning home. He left with just a backpack? He had $1000 worth of stuff SOMEWHERE.... one person does not need $1000 for gas and food from WY to FL....
Had he NOT gone home, and instead fled in the van? He would be easier to track/find IMO and he was well aware of that. He needed to get home in that aforementioned window, clean the van, get rid of whatever evidence there might be, and get on the run before even his parents were aware of the true circumstances.
IMO, LE know he is not in the reserve but because of major errors in their handling of all this, are doing it to appear productive. BL is long gone and they know it's because of their negligence, again, my humble opinion.
He also is LIKELY not dead by suicide. He appears, again IMO, like an ego maniac. They're usually not the type - too proud. His distain for "human beings" in his social media posts alludes to this.