Who ever heard of the Senate passing legislation to "protect" a prosecutor? It's an absurd notion on its face. And coming from an erzat 'Republican' against a Republican President makes it even more absurd.
All Flake is doing is to prove that the whole Mueller clown show is not about any kind of justice or investigation. Rather it is obviously a purely political 'hit job' on Trump and anyone around him. I mean seriously, what dog does Flake have in the Mueller probe? Why is he so passionate about it? Is he stupid enough to really believe that the Russians elected Trump? Then why after two years is there no evidence?
Flake doesn't give a damn about Russia. He just doesn't want to take any pressure off of Trump from any direction. If Mueller is hindering and interfering with Trump's ability to do his job, then Flake, like all Democrats, wants Mueller to be installed permanently as a permanent prosecutor of Trump, forever, regardless of any results.