He explained why in his other statement - when there is a witch hunt investigation (unprecedented) why bother. He even addressed that he criticized taking the 5th previously.

I believe he didn't testify in either impeachment for the same reason. Takes valuable time and money away when there is no fear of actual prosecution. There can be political damage though if people can run out of context sound bites.

no reason to talk to someone who is desperately trying to cobble something together when she has made clear she is just trying to find a way to put him on a hook.

He is a fast learner. Been watching close up how the real criminals do it.

Any competent lawyer will tell you to stfu

It worked for Lois Lerner.