That entry doesn't explain why Hawks can use even blood magic in front of templars and there would be absolutely no reaction from the harshest templars in Thedas.
An excerpt from the twelve entries:
"It is well known that the Veil is thin in Kirkwall, small wonder given the suffering in the city. But we've discovered the magisters were deliberately thinning it even further. Beneath the city, demons can contact even normal men. Did they seek the Black City to compound the madness of their previous efforts? Or was it something else? We've found a chamber where the Veil is at its thinnest, long-since looted, but the power is still there. Tonight we will go there. Pray for us. Pray for us all.
—Hidden behind a rock with curious markings and signed, "The Band of Three"
The barrier to the Fade is purposely thinner in and around Kirkwall, giving rise to greater Demonic influences including Pride, Sloth, Desire, and the rest. Deception and the growing power of Blood magic there dulls the minds and hearts of humankind in that area, to the point where even Hawke does not clearly see (eg; Merrill's useage, harlot w/ Blood magic, etc), as well as swelling the ranks of Abominations.