We really hesitate to recommend a service dog for someone who has anger issues because having a service dog is difficult enough without adding extra problems. An exception is sometimes children with autism, who often have impulse control problems and difficulties in controlling their emotions. 

With children with autism, though, the parents are usually in charge of the dog (rather than the child being in charge of the dog), and thus the parents may feel comfortable creating safe spaces for the dog to go to, while at the same time using techniques to help teach the child appropriate behaviors. When the situation is an adult who cannot handle their anger issues 100% of the time in an appropriate manner, though, there is not another adult who can protect the dog (or protect the person who is interacting with other people).

Issues with anger control are often complicated by PTSD or other psychiatric disabilities, which makes the whole situation more complex. My father spent forty years leading chemical dependency groups, and he once told me that every time a group member had taken an anger management class, they reported that it was very effective and it often was the best class they had ever taken. Perhaps it's better to take an anger management class before looking into getting a service dog.

In general, we hesitate to recommend a service dog for an adult who doesn't have full control of their anger.