Homer Laffoon, 22, reportedly claimed in a court filing that there isn't enough money to satisfy the numerous lawsuits stemming from his mother's fatal crash.
The singer's appearance at the February ceremony marked her return to public life nearly two years after revealing her stiff-person syndrome diagnosis.
The Pulitzer Prize-winning screenwriter also argued that his famous children, including "Girls" star Zosia Mamet, didn't benefit from his industry status.