Is that really the case? Wouldn't this kind of breach be best used silently. They could have used this access to alert those targeted by the regime ahead of raids etc..
This just seems like letting the regime their front door is entirely unlocked.
If the goal is deterrence - as the attackers seem to be claiming - quiet use is counterproductive.
The proposed use is doxxing of police and intelligence employees who are involved in political repression, including revealing the apartments and cars they use when on the job.
If the population is fed up enough to be willing to resort to violence, simply releasing this list with no prior warning would likely cripple the security apparatus, and make everyone think twice about participating in it in the future.
If the parties involved had similar powers possibly yes, but their government is already a lot more powerful compared to the people, so they need to act quick in order to disrupt the status quo, possibly also gaining some time.
It is also safe to assume that if the hackers have access to the conversations of all people, then also the government does, so it's entirely possible that the police already have their targets set and could soon escalate this to arresting everyone not explicitly pro-government, hence the need to disseminate the information to create some panic in the high ranks while buying some time.