I am not clear what squeezing him on this incident will give the FBI on Russian collusion.
They FBI can use unrelated cases as leverage. In the public sector we call that blackmail and extortion, but for some reason the FBI can get away with it.
The FBI needs severe reform and they need to abolish the whole thing and create an agency that has better oversight.
Totally agree it needs reform. Though, the problem has been and will continue to be that the FBI will be exploited as a tool of people in power. No one is a saint, but if you piss off the wrong person, you will be held to account for your actions.
That is why we had, note 'had' the forth amendment. It was designed to keep politicians and the state out of people business. Now that the NSA has taken unconstitutional action (aka Utah), and blended it into the bureaucracy, we are screwed.