I completely agree with all your points here. My only comment was that this prosecutor would have been disbarred had he not presented the "unhelpful" evidence to the GJ. I would say there would be zero way in hell that would ever happen. A DA has to seriously fuck up for it to reach that level, and look how long Nifong got away with it? How many lives did he irreversibly ruin both in that case, and cases we don't know about?
I get that you have more faith in the system than I do, and I actually appreciate that. However, due to some poor life choices I made in the past I was on the wrong end of a federal prosecutor. You read about my case in the news. While you could make an argument either way if I should have even been caught up in the legal proceedings, I will say the one thing that made me completely distrust any government or legal process was what the fed prosecutor told me right to my face with zero shame and other defense attorneys present. "We freeze your assets so you can't afford to pay counsel. Then you have to settle. lol". And the lol was actually what happened - he laughed in my face. Luckily in this case I broke the law, and I had expatriated assets I could use for my legal defense. I largely won, but absolutely would have had my life ended if I didn't have $100k for my defense sitting offshore by sheer chance at the time. This annoyed the prosecutor to no end, because he actually had to fight a case vs. simply extracting a favorable settlement out of a defendant that had zero options.
That is when I realized once and for all that all the stories from the "crazies" about how the government - specifically DAs - abuse their power might actually be true. I've paid a lot closer attention to the "high profile" cases these days, and in almost all of them I can spot severe overreach and some prosecutor not giving a shit about justice.
So tldr? This guy did pretty damned well. He knew there was no hope of a conviction, but still presented the proper (all of it) evidence to the GJ to let them decide. He didn't railroad the guy because it was politically convenient, which was a surprise to me.