Supposed Austrian commenter explained that the idea was that the less stressful atmosphere made the inmates less violent.
Or in other words, it's customized rehabilitation for very specific criminals. If I had to guess, it's more of an asylum than a prison, kind of a haven for people who are not criminal or violent by nature but due to an incredible amount of pressure or bullshit ended up going, ah, a bit postal. Locking those people in a concrete chamber is only going to aggravate the situation; placing them in a secure but comfortable environment where they can shake off their rage and maybe get a taste of something to better themselves and strive for once they've spent their time in solitude might be better. Or it might be a fucking ridiculous waste of money.
Or, the whole thing may be a hoax, ho hum.
