Well after listening this it definitely does give us a better idea as to Brian's personalty. I always thought that he could be sarcastic or a smart *advertiser censored* as his cousin puts it. That's one thing that Clint said that apparently rings true. Randy had mentioned in an interview Clint saying how Brian could pretty much speak his mind to anyone and at times and possibly get into an altercation.
I also find it odd that out of the 3 family members they talked to they all seem to think Brian is dead and maybe got into trouble somehow with the wrong people but at the same time they think Clint may know something. Lets say that Brian walked out of that building was walking down the street and mouthed off to the wrong guy or guys and was killed, how would Clint know anything about this ? Given that scenario I also have to wonder if someone did kill him I don't find it likely anyone is going to take the time to stick around too long let alone hide his body.
This is why Ive been more and more of a believer in the theory of potentially some shady meeting/deal gone wrong happening in the construction site. This would be the simplest way for Clint to have knowledge of something he wants to hide without being directly responsible. The description of Brians personality in the podcast does make it seem like theres a possibility he could have involved himself in some high risk behaviors.
This theory explains Brians disappearance, Clints silence, the dog tracing the scent out the door (ie possibly into a car), etc. It fits so well with so many details which is why it has now become my #2 theory behind an accident in the construction site (which still remains #1 IMO).