For recreational purposes most likely? It's sad that this highly intelligent person has died, but drugs are a thing. And people do them, and sometimes it gets out of hand and those people die. There's nothing too unique about this.
I don't mind theories, but just throwing that out there with literally no supporting evidence is just a waste of energy.
I do agree that the timing is very suspicious, and i'm sure this will be construed as some kind of conspiracy- but realistically, considering the kind of death; I think it's most reasonable to accept that this was a standard mixed drug overdose death.
[1] http://www.psychologytoday.com/blog/the-scientific-fundament...
[2] http://www.mirror.co.uk/news/uk-news/the-crackademics-more-t...