I understand your point, but I'm not so sure. Minds and emotions are so complex. I agree that it is very, very interesting that he didn't run. I honestly thought he was Belize or Boston or Berlin.
Anyway, just to make the opposing argument.
He was the only person who knew what evidence might have been left at the crime scene. Also, Gabby's remains weren't found on a remote mountain top, but only a 5-minute walk from a road. He was an outdoorsy kind of guy, he wasn't fond of people or crowds. (That was in one of his Instagram posts I believe, him complaining about too many people in the parks.) The thought of prison might have been his worse nightmare, support be damned. Who knows? Maybe he didn't want to face his family with the truth.
The question of remorse is troubling, too. Murder/suicides are not common, but they certainly happen sometimes. How many have a two-week interval between the murder and the suicide? Is that
normal? I have no idea, but he waited until it was kind of obvious he would be captured. That's not remorse, that's fear. JMO at this moment, ofc.
The Tragedy of Murder-Suicides
I've also wondered when the media blowup first started and if that might have played a role in his decision. I honestly can't remember. Was that before the 13th? It all hit the web fairly quickly.
**Edited to add a link.