to me it seems pretty clear that he was in a manic state.
a) he changed his name sometime prior to one that most people would find bizarre- I like creativity as much as the next person, but he was not in the entertainment industry. this seems, like a manic action to me. neo maximus? he didn't tell his family, or most of his friends. this sounds like a relapse to me.
b) bizarre phone calls referencing the periodic table of elements, moving south to florida or texas, people are after him because he sent some "emails", and he wasn't loved enough, all in short period of time, while running.
c) someone matching his description was seen climbing into someone's second story window nearby, asking for someone named mason, a person charlie also had plans with, that same evening.
d) his shoes are found, with no evidence of foul play. soon (days or over a week) after, in cold weather, someone matching his description is seen shirtless and disheveled nearby approaching a semi. bad news. do I believe this was him? yes, because it struck the man as very unusual, and when he was possibly seen climbing into someone's window acting strangely, he was also shirtless in cold weather. it is not uncommon for people to remove their clothing during a manic episode.
It is obvious this family loves their son, very much. but it seemed like there was some denial regarding his behavior on his final day. I have had exactly ONE very manic episode in my life. it lasted, approximately one month, or so. never before, and never again. I had gone off some medicine that helped me sleep, and I didn't sleep for a long time, and I think that is what triggered it. it was about eight years ago. my point is you don't have to have a history of events like this to suddenly snap out of reality, and having a bipolar diagnosis and not taking medication it surprises me they don't take that possibility more seriously. they say it wasn't the charlie they knew. I'm sure it wasn't! people are not themselves at all when they are seriously manic. I'm sure the charlie they knew, knew what makes sense and what doesn't. but the charlie that evening, did not.
where is now? well. I don't know that I want to speculate overmuch bc I don't think the family welcomes speculation it seems like, from the ID show. suffice to say. that I think truck drivers who pick up shirtless, disoriented young men have a small chance of not having a safe and friendly ride on their minds. and if the first one or two drivers did, the third may not have.
my hope, is that he is alive, and will come home, but I don't know that is what I really believe. that last possible sighting a year or two ago, does bring hope.
people in a manic or psychotic episode often read into things to an extreme degree and reference cryptic connections that strikes others as "crazy". They often sense conspiracies. it wouldn't surprise me if he started to mix up his own identity, with his old gaming identity, and reference the game half life with the table of elements, and even, legally change his name to neo, his gaming name. it shocked me that this was kind of laughed off by his sister, like it made sense. legally changing your entire name out of the blue is a big deal. when I was in a manic state, I recall I sent some strange emails out. if he thought someone was after him for emails he sent out, it wouldn't surprise me, the person receiving the email, if there was any, probably just thought, what the hell?
And your suggestion makes total sense.