She was 30 years younger than him and roughly a similar age to his kids. He had dementia and possibly couldn’t remember who his kids were let alone that they called if he called. It’s not all that surprising to me that his offspring weren’t in frequent communication with them. They were probably just waiting to get “the call” that he had died.
Maybe somebody noticed that she hadn’t been in yoga or hadn’t posted on social media, but that hardly is reason to send in the swat team. One could never have imagined the scenario that unfolded. Stuff happens. Maybe if they hadn’t lived in a gated mountain compound somebody would have noticed something earlier.