All good points and possibilities. I agree with the dynamic you describe south of the border. I also agree with your conclusions stemming from that.
My main contention with the footage that was published is why did the masked man on the Nest cam go to the front door with such purpose? He didn't seem to be aware of the camera so it wasn't to just disable it and the front door was in a mostly enclosed, secluded brick vestibule. Many other first story entry options including a side door to the garage with an easily breakable pane window on it. No need to go to the front door there unless he wanted to go to the door itself. It had a welded security door with a deadbolt and he went for that hard access point displaying what appears to be a firearm, which I believe was for intimidation and coercion (I was confused by his holster and carry choice, why not conceal carry and use the sidearm when necessary?).
As far as we know the security door was not breached or damaged and the decorative windows on either side were not broken (common vulnerability to reach in to open single cylinder deadbolt, takes a few seconds to gain entrance to most homes, in NG's set back secluded home the sound of the glass breaking would be negligible). Either the front door was unlocked, he had a key, lock pick, or he used coercion to enter the home;
....banged on the door with a ruse --cam was disabled at that point--a startled elderly lady finally checks and opens the door - not my PERSEC but it happens- and he brandishes the gun and she complies, maybe a struggle ensues out of the door or he hits her to show her he means business and underestimates the blow to a medically compromised 84 year old - criminals aren't smart....
The latest I've read in reports is that investigators have not confirmed any signs of forced entry (if someone can link something to the contrary I would be grateful).