I don't think you should be sad about this, he seems to care about you, him not making any move on you and keeping things casual seems more like he is showing you respect and doesn't want to scare you off, as FOAM said now he probably doesn't know how to proceed with you for the next step. The fact that he is into metal and tattoos doesn't mean at all that he cannot be interested in someone who is not into these things. Maybe the next step is yours to make. Of course there is also the possibility that he only invited you because he was lonely as well, that you should keep in mind.
Also, from my experience it is true that people with schizophrenia can be confusing, which explains that you have trouble figuring out what he wants from you. Also from my experience, people with schizophrenia who uses drugs and alcohol as well as their medication aren't bound to make your life easier. Just so you know.