@BronzeTongue has laid out the case more eloquently than I usually can.
But I'll try again.
Nobody just puts their cards out. Not in this setting, not in World of Darkness.
The Council currently has multiple traitors, and thats not counting people who may be loyal to the Council but can be induced to share information they learned in it; Dresden himself talks to his allies about some stuff the wizards tell him for example.
In a setting like this where knowledge is power, controlling access to it matters.
You cannot unspeak information, or unshare it.
And once you put it out there, it will go wherever happenstance carries it.
And information in the hands of hostiles is not in our interests.
Thats a distinction without a difference.
The Thousand Hells have commonalities, but they are all individually different from each other.
Furthermore, Yomi Wan is not the only afterlife/Hell(s) in the setting, combined or individual.
The rules in Yomi Wan(World of Darkness) are different from the rules of Lucifer's Hell(Dresden Files), which is itself different from the rules of the Hell/Underworld run by Hades(Dresden Files).
There's also the Dark Kingdoms (World of Darkness), Malfeas(World of Darkness) and wherever the Southbound Train from Ghost Story goes(Dresden Files). They're all Hells and afterlives.
But how they are run and who runs them differs.
The proof of that pudding is in the eating, when people draw their own conclusions from the data at hand.
Not the ruler insisting strongly that her own Hell is Different(TM).
This is not just what Wu Min believes; the people reading her reports will look at the raw data from her and Morgan and Dresden and Carlos, not just her opinion. And her opinion differing very much from the data speaks to her either being whammied or bamboozled. Which would make her opinion worthless anyway.
Why?
The Big Players we know of, the angels, Mab and Odin, Titania, the Great Dragons and the Outsiders, Lucifer and the
Denarians Fallen and people in their weight class already know whats up or can make an informed guess.
Those less privileged bad guys like the Fomor and the Red Court and even most of the Yama Kings who dont know shit have to spend time and effort and resources to dig up any information thats available, which is time and effort and resources they dont have to otherwise fuck with us and ours.
I see no reason to make things easy for them.
And I will reiterate that whatever we put out can be used by enemies.
Just as a most recent, part of the reason we were able to outmaneuver Broken Seeker is because we were able to maintain information superiority over him/it. Without it, we'd have had significantly more worry about getting betrayed.