While I understand that he did not realize what he did, and that it was the schizophrenia which caused him to do what he did, I do not think it is best to release him. What if something happens and he is unable to take his medication, he could easily slip back into madness. The medication does not cure him, it is a band-aid. A very good band-aid, but a band-aid nonetheless. Besides the scenario mentioned above, could it not be possible for his schizophrenia to evolve and tell him that his meds are brainwashing him and that he should stop taking them? I pose this as a question, because I will admit I don't know if this is possible. I'm on some mental medications myself (fortunately for nothing close to as serious), and while very effective at what they do, they are far from perfect and do tend to weaken as the day progresses.
To those who still do not understand what he was thinking, I'll summarize a scenario I read someone post elsewhere:
You are at the park with your family, and you see someone attacking a loved one. You instinctively react and kill the attacker with your bare hands. However, it turns out that the attacker was not a stranger, it was a friend. And he was not attacking the person, but giving them a hug.
The point is that to Li the parts of the brain which would tell him that aliens are attacking and that he is the Second Coming of Christ is unbelievable were not working, and at the time he thought he was doing a noble thing. God forbid, if I ended up doing a similar act due to schizophrenia I don't think I would want to be released in fear that I could hurt someone again - regardless of how effective the medication was at controlling any voices. Supervised walks in the community are fine, but anything else and I believe he could be a public threat.