He may not have told them he lost the position. Consider this, he lived at home till 30 (29 I think). He might have planned to say, I am so homesick there, I want to stay home. Or, "there are so many drugs around the campus, I can relapse", or something else. I think he would have presented it as his decision.
He always lived at home, and the only time he left, and lived in another state for - what, four months? - he now stands accused of killing four people. I was thinking about it, what a huge failure living outside parental home turned out to be for him.
As to returning home being a failure, yes, in a way, but these days, about 16% of adult US citizens live under the same roof with their parents, so it is less surprising.
P.S. knowing how surprisingly little it costs to be in a pH.D. program in the US, potentially, he could have asked parents to support him until he'd find another job. I don't know if the financial part would be unsurmountable for them, but in contrast to Master's that is expensive, PH.D. is usually room and board and books. He would not have been kicked out of the program for failing TA, I presume. Maybe I am wrong, but usually pH.D programs are exceptionally supportive of their students.
The U.S. Census Bureau today released estimates showing there were 10.9 million one-parent family groups with a child under the age of 18 in 2022.
www.census.gov