Speaking to Cade's superiors would likely yield a similar answer: they don't know. Nobody knows what to do with him. If he were a dog, he would have been put down years ago. They can't keep him locked in a cell for the rest of his life, just in case he does something again. If they send him away, cut off his lyrium supply, he'll go mad and die alone. It is merciful of them to keep him around, but he is a useless weight that drags on the Order and he knows it.
Remaining out of sight and out of mind is the best compromise, as far as he's concerned. Nobody has had a problem with it so far.

It's only when receiving this gentleness that Cade realizes how desperately, achingly lonely he is. He manages to relax slightly, with a subtle sigh, when Zevran's fingers brush the top of his neck; nobody has even spoken to him for days, let alone given him positive attention. Despite how uncomfortable this is, he finds himself wanting it to continue, if only to maintain the illusion that he is cared about.

Eventually, his doubt gets the best of him. "...why are you doing this?"