I think "outsider knowledge" is a lot like Jon Doe citizen seeing Top Secret CIA stuff (in this case the CIA are the "outsiders"). It is okay to know the CIA exists, it isn't okay to know what they know.
And HWWB isn't actually its name. It is more of its "name you want facebook to display." Sort of like how the CIA is also referred to as "The Company" or "The Agency."
The rule about Outsiders is more that "Don't try to summon them to gain knowledge since your magic probably won't work! They'll step right through your circle and eat your face, then your neighbor's face, then that cute girl down the street's face... Don't do it!"
I got the feeling it was as much his name as "mab" is mabs name. Its what he gives out to people, not his True Name.
And yes, its ok to know that there is such a thing as Outsiders. Beyond that though? Its a Bad Thing.
Idk i think they would fit in a circle. even do your bidding to an extent (see HWWB being a hired assassin). And twist you horribly in the process. Pretty soon youre summoning him and his 14 cousins into the prime material plane to be your servents and then all of a sudden you don't exist anymore and there a massive OUTSIDER Gate on your front lawn and the sky is weeping blood and Cthulu just ate the moon.
The laws seem to make slippery slope arguments a reality instead of a fallacy. You do this, you do it more, until it snowballs ridiculously out of control and something abjectly horrible happens.