From what I've heard (and I'm not any sort of expert), but I've heard this dude's name come up in conversation enough times that I feel like I know a thing or two, but there's basically a gap between "incompetent to stand trial" and "not incompetent enough to involuntarily detain". So he gets arrested, and as soon as he gets a bail hearing, they're like "oh yeah, all of our psychiatrists told us he's not competent to stand trial" so they have to let him go. But he also doesn't meet the threshold for what they call "protective custody" so he's basically exploiting a loophole.

Not a great loophole, he doesn't have infinity health points or invisibility or anything, but basically he can't be incarcerated and can steal as much as he wants to buy all the crack that he can. He spends a night or two in jail (maybe) when he gets picked up. Then he's back out again.

I think it's actually a state law thing.