Philip, who testified against his father for the prosecution told "20/20," he never wanted a public trial, or to set the groundwork for a criminal case against his father.
"There are people who probably would say, 'Well, how did I do this to my father?'" Philip said. "Quite frankly, what I did was help my grandmother, and he brought this upon himself. ... I don't think that there was anything innocent about what was being done to my grandmother."
The public trial cast a spotlight on an epidemic of elder abuse. Up to 2 million Americans, age 65 and older, have been victims of abuse or neglect by their caregivers, according to the National Center on Elder Abuse, and 60 percent of those cases are by a family member.
"[Brooke] didn't choose this. ...Certainly she wouldn't like what's happening, but look what it's doing, in terms of addressing an incredible cause," he said. "And I think what the result of what we're in the fray of now, and how this will extend beyond Brooke, is really personally very important, about how this will inform the greater discussion of elder justice."
In her final years, Astor was plagued by confusion and disorientation that left her vulnerable to the deception that brought the family to criminal court in a trial that lasted six months and left her son facing prison charges.
ABC News' Eric Strauss and the Associated Press contributed to this report.