You have completely miss understood the complaint.
The complaint is about the FAA hold passenger items after the emergnecy is over while they "investigate"
The process should be
Evac -> Fire Dept clears the plane > Airline gets passengers there stuff
it should not be
Evac > Fire Dept > NTSB Looks at things > FAA Looks at things > Someone 3 years later Passengers get their things
because the FAA as the latter policy, people will be more prone to try to take their stuff, then if they knew once evacuated they would get their belongings before leaving the airport, not at some undetermined time later
FAA Policy increases the danger for everyone.