Yes, I disagree with the way you are framing this. That is why I once again simply stated my opinion that we see politics at play relating to Strzok in response to your post. I have been rather clear about my opinion.
You apparently believe that having political opinions about presidential candidates during a presidential election represents "clear personal animus." I disagree with you. In my experience, most individuals in law enforcement and criminal investigations have strong political viewpoints. However, they can usually set those aside and do their jobs.
Also, with most investigations, if one searches hard enough and so desires, one can usually find something they can use to attack the investigation's credibility. Happens all the time. Again though, that does not mean each attack should be taken seriously.
And I have no problem with Congress investigating. But when it dissolves into politics, then one can call it that. What I saw yesterday was politics. And it wasn't a good day for the Republicans on that committee.
I disagree with your addition of the word "righfully." And I would argue that the credibility of the investigation is in question because Trump's legal team along with his political supporters have decided to attack the investigation's credibility. Just as Clinton did with the investigation surrounding her. It is the same playbook.
Strzok is just the pawn the Trump team is currently using. Yet, they didn't really succeed attempting to discredit him yesterday, which was their sole intention.
I too have extensive experience with criminal investigations and/or law enforcement as a prosecutor.