hmmm ... serious charge. Worth looking into.
My research is shallow so maybe no good, but it found: all these main people (inc Rosen) are Democrats so the lumping of some perceived flaw in this instance as a broad Liberal smear seems off, but I need further info. The complaint came from some attorneys, so the judge was required to address it. The complaint was due to comments made by attorney Rosen while he was (recently) campaigning for office himself. During that campaign, he decided to play the anti-semitism card and specifically featured this very case as an example of it. This probably was an error on his part, as relates to this separate prosecution, (because he made this case about anti-semitism, even though that was not in the charge.) Since the case theoretically should be pursued on the facts of the actual grounds/actions committed and not cultural add-ons, the defense lawyers objected to his stated positions as coloring the emotions of the case before it even began. When confronted by Rosen's actual words, the judge decided that he should recuse himself due to self-stated public bias.
Again, my research is shallow, but the above is the coalescing of several government and news websites on this. Individual websites DO project their own biases, but this is the information that I got with the emotions stripped out. The bottomline is that Attorney Rosen was not denied because he was Jewish, but because he had made public comments about the case which were not directly contained in the actual charges, yet were very emotive to potential jurors. Being publicly "too close" to cases is actually fairly common grounds for recusal but this is more so if one is in the judging position than the prosecuting. The aura of objectivity nevertheless is preferred.