The people who should be sued in this incident are the pax who picked up and lugged their carry ons with them. they really did visibly endanger lives and go directly against lawful instruction from airline crew , which I think is some sort of offence.
Maybe the defending party can county sue these individuals for endangering life and prolonging the anxiety , fear terror, mental distress the pax are suing for in the first place.
Oddly I would bet that in most cases its the same group of people who think only of themselves.