A true jury nullification occurs in a trial, which would stop this from being brought again due to double jeopardy. That's one of the things that makes jury nullification so powerful. This, on the other hand, is a pre-trial rejection, so they can try again.

This is before an indictment is even filed. Jury nullification takes place at the trial deliberation stage, after arguments have been presented from both sides with a judge presiding. This is no where even there yet.

As you don't have any of the details, you cannot judge whether this decision is congruent or incongruent with the law (ie would most impartial judges have made the same decision). There could have simply not been enough evidence to indict in the first place. Or there could have been key evidence that was excluded due to violations of civil rights, improper procedures, etc.

I very recently sat on a jury for a criminal trial in which we found not guilty. After my service ended, I looked up the case docket and found several details that pushed my personal analysis to the defendant likely having committed the alleged offense in my personal balance-of-probabilities reasoning framework. But the evidence and arguments presented at the case were so lacking (due to those details having been excluded in limine, as well as needing to meet the standard of beyond a reasonable doubt) that we jurors deliberated for all of five minutes because we had started off in unanimous agreement of not guilty.

(and just in case it's not clear, I have no regrets about that! Even knowing what I know now, I would have chosen not guilty - the government simply didn't meet the burden of proof, and our civil liberties are important)

Getting back to this case. If we take it as a given that grand juries readily indict as the bar is low and prosecutors generally make sure to have their ducks in a row, we are still left with multiple possibilities of how politics might be involved here. Which is more likely - that the prosecution presented a well-substantiated argument that the jury then completely disregarded (ie "nullification"), or that prosecutors were politically encouraged to press this despite glaring holes in their case?