I would like to answer your original question if I may: "is it appropriate to go directly to the bishop"?
In the case that you have described, I do not think so. My reason for saying this is: discernment is exactly why we have bishops in the first place. We, the laity, are supposed to be obedient to the Church as a whole, not to get involved in every ordination or every decision made by bishops or synods, etc.
It's one thing to be vigilant and concerned about various enactments of the Church, to be involved in decision making processes involving matters of every day parish life. But to involve ourselves in the priestly orders, and who gets ordained and who does not seems to me to be "meddling" in bishops affairs unjustly.
Bishops are bishops precisely because they have shown discernment and we are to trust them in these mundane matters. I would say that unless this person has done something (Provable!) that is particularly egregious, it would be best to stay out of it.
God bless you.