Whether you particularly care or not is one thing, but remember even the US has something against cruel and unusual punishment, and so has Sweden IIRC.
First of all, Breivik is in Norway.
Second, the Swedish prison system has a huge problem where inmates, mostly people subject to pre-trial incarceration, are subject to near complete isolation for extended periods of time. They are locked up into the equivalent of a bathroom without any TV/Radio/Newspaper/etc at all. They aren't allowed to socialize with other inmates, talk with relatives and so on. The only human contact they have may amount to hearing the person who chucks their food-tray into their cell.
Even if the courts decide that the isolation isn't warranted anymore (such as happened after an suspect was subject to isolation for years during an incredibly dysfunctional, corrupt and largely failed police investigation) the prosecutor and prison authorities can disregard this and unilaterally decide that the suspect needs to be "isolated because of security reasons".
All of this is because of the desire to prevent the suspect(s) from working out a common narrative to give during police interrogations (which most of the court case is based upon). Despite years of criticism from various groups, including the UN and ECHR, politicians have been more or less completely apathetic and indifferent to this form of institutionalized psychiatric torture. Only this year did someone of any importance give a damn and a parliamentary investigation was started around the subject.
The Swedish prisons where people serve their sentence are on the other hand, usually, far less strict and more humane. There inmates aren't subject to isolation nearly as often. Perhaps more importantly they aren't subject to the uncertainty of when the trial will take place and what the judgement will be, which is often one of the largest sources of anxiety and suffering.