Where does it says that? Show me a panel. If you are talking about the "burden" thing. When He was having the panic attack.He ran outside so that others would not get hurt, as matter of fact. So, there was no negligence on wally's part. But,the alarm rang the heroes got outside before wally could do anything to warn them his powers went haywire. So, it is involuntary manslaughter. He had no control of his actions, at the moment of crime.
You can say wally shouldn't have put himself in that kind of stress to begin with. But, wally had no idea he was. He was put in a strange place with others to "heal". He had no idea if it was just a coercive tactic to keep him isolated in by the "heroes". He had no idea how this was supposed to help him. So, he decided to investigate to know if the place was real or facade. Sorrows causing him to have a panic attack was entirely an accident or out of his control. He had asked for clarification. But, they didn't give him a satisfactory answer, but playing the pr answers without evidence. So, Wally doubting was entirely on them.
If you are blaming wally not telling others prior to the event. Well, its part of his privacy. Neither did barry his mentor did it. As matter of fact wally was minor when he got his powers. Barry and whom ever was responsible for wally at the time has to be blamed for that. Since, it wasn't wally's decision to take at the time. For example, superman had told the league regarding Jon's erratic powers early on. You could say wally had opportunity afterwards. But, he was following the standard set by barry. So, barry and all other speedsters will be as guilty.