I would be cautious about infantilizing someone. The ageism in this discussion is concerning.
Just off the top of my head I (in my 60s) know people in their 70s and 80s who are maintaining rigorous schedules in the community band, who are leaders in the garden club, who still work, who maintain their own properties, who put in a lot of hours doing childcare for their family members, who drive large RVs, etc.
My former neighbor, at age 90, used to have a large vegetable garden each year and SHE would be snowblowering my driveway while I was still lying in bed. She wrote two books in her 80s, on a computer, and still drove 100 miles a few times a month to visit her sister.
There is no indication that NG had any cognitive decline, isolation, loneliness. She had mobility issues but she seemed to have a fairly active life. She still owned and presumably drove a vehicle.
Using the same old FB photo is nothing. I personally have a 20-year-old photo on LinkedIn because I don't like images of myself.
Asking how to get to the airport? Maybe she wanted to greet someone. Maybe she offered to pick up someone. Maybe she was looking that up for a friend. She didn't need anyone to "arrange a shuttle" for her.
NG is/was not a doddering, incompetent person, based upon anything I've read. It was stated when the disappearance was first announced that she was "sharp as a tack." Lots of people look up things online out of curiosity, not need or desperation.
As to the porch pirate, it didn't unnerve her too much as she didn't move, hire security guards or purchase a Ring subscription.