Olivia Nuzzi, the author of the New York article said she spoke to family members for those comments. Ground News says the org is left leaning, and highly factual. it's eye opening.
What makes them credible sources, though? We don't know who they are, and sometimes all we get is "others say".
If he's in some kind of cognitive decline, let someone come forward and put their name on that determination. Better yet, a doctor or someone qualified to do it. Everyone has bad days.