Lately I've been more and more of the mind that an obsessed stalker best explains this case, given what we know.
I have heard many times related to this story "Who kidnaps an 84 year old woman?"
Well, nobody, really. What's the point? It's a ton of hassle and now you have to care for a terrified elderly woman with health and mobility issues.
Unless you are a totally obsessed stalker of SG. Then this is a passion project.
In this scenario, this is a person who obsesses over SG and maybe other celebrities as well. That could go either way. So he sees the feature on TV about SG and NG that we've all talked about. That puts the idea in his head to check NG out, if he hadn't already.
In the course of that he learns a TON:
She is 84 and lives all by herself. Quiet neighborhood, houses spread way out, pitch dark at night, lots of elderly people (lower chance of someone being up and about at 1-2 AM), tons of shrubbery and trees to hide in, house partly blocked from view in road. House recently listed (according to reports) so he can go online and see photos of every room and some of the outside to get a good working idea of the layout. Beds/baths, where doors and windows are.
Even when a listing is taken off or a house is sold, most popular realty websites retain the language and images of the previous listing. I think you can request removal, but this is on a site by site basis and is likely time consuming and tedious, and in reality almost nobody thinks of that. Especially in a home where the doorbell camera subscription lapsed. I doubt that was done.
Biggest nugget of all for this psychopath: this is the same house SG grew up in. And he can easily gain access to it and her mother.
Nobody on this planet is likely to know more about SG than her own mother. Phone numbers, addresses, stories about her growing up, candid photos, videos, everything. And (from the POV of this stalker) this crime will all take place in HER (SG's) house.
Aside from SG herself living alone with unlocked doors in the middle of nowhere, this is the softest target a stalker could dream of.
This could also explain the 40 minutes spent inside (which I mentioned previously I don't totally buy but I'll accept it for the purposes of exploring this theory). The initial stage would be subduing NG, looking around the house for whatever he could find about SG and just spending time in what used to be her space.
I know it sounds gross/creepy, and it is, but this is how a lot of these people think. To defeat them you must think like them, as distasteful as it is.
Maybe he finds that instead of the smiling sweet grandmother he saw on TV, NG is angry and combative and will not cooperate. Maybe she refuses to tell him anything, including something as seemingly small as which room was SG's. So he snaps. This could explain the blood. Maybe he hit her to try to force compliance. He won't want to seriously hurt her, because he needs her to be ok for later when he will try to wear her down and get all the info he wants. But he has to scare her because she is yelling at him, maybe even insulting him, but most importantly she won't give him anything he is demanding.
Maybe he tried every angle to get info from her in the house before taking her away. He would want to know: which was her room? His sick fantasy is getting ruined! She won't say a thing, and maybe even fights back somehow. You can imagine his anger.
Meanwhile, tick tock. There's the 40 minutes spent inside.
Eventually he realizes this is all pointless, but he was always going to take her, because he figures he can get most of the info he wants over the course of time in a more controlled location. He's also about to become one of the most important people in SG's life (in a sick way) because he has her mom. This is stalker 101: he has power over her now AND he likely thinks he will get info out of NG eventually.
This explains the blood. It explains nothing being stolen (he wants NG for the info and knowledge she has). It explains no serious ransom note (the point was not money). It explains nobody coming forward for the million dollars (he acted alone in this scenario). It explains his seeming "amateur" behavior on the porch (maybe this is his first time doing something like this and he's off kilter mentally and likely very nervous and worked up because of everything I mentioned above).
Stalkers want information about their target and any type of control they can get above anything else in the world.
The only silver lining in this scenario might be that he would almost certainly want to keep NG alive and well, because the whole point would be her being a connection to SG and him having control of her. He would want to hear stories about SG growing up. Her favorite things. Everything about her. He would need NG alive and well for that, and IMO this was the entire point of his operation.
A final word on him getting away with it. A lot of times first-timers or one offs don't follow any established pattern, so they can initially be harder to catch. Since they don't follow the A-B-C crime profile they can slip through the cracks. But they eventually slip up. He'll be caught IMO. Likely relatively soon.
All just my opinion, but I'm starting to think that something in the neighborhood of the above scenario is the best explanation, given what we know.