Government employees whether grand Pooh Bah of whatever or peons cannot claim 5th amendment protections either to congress or courts in the context of their official actions. As private persons they can. I wonder if this out-of-the-blue resignation is a reflection of this?
I believe they have sovereign immunity or qualified immunity against good faith acts connected either their official duties. It’s a pretty high bar to clear although I think it is unnecessarily high.
It’s the reason why judges for example cannot be arrested for a sentence no matter how ridiculously light it is for the defendant committing a crime. Or a bail decision where subsequent crimes are committed are. Or the liability of the judicial officer because of this qualified immunity.