The TSA has an administrative process for filing claims (like most agencies).
They went through that and it was denied.
There is no claim in that lawsuit that the process was not fair or reasonable.
It's a bit ridiculous that the only process for this sort of thing is a recipe for bias and lack of justice. If an agency that is known for incompetence and overreach is simply allowed to investigate itself, without any independent oversight, I don't have much faith that complaints are given a fair hearing.