Steven again they're distinct things:
Schizophrenia can cause people to harm themselves or others.
Heavy cannabis use increases the likelihood of an individual developing schizophrenia or having psychotic episodes.
Terrorists use drugs, including cannabis, for short term highs (in terms of mood) and/or to prevent them thinking about what they're doing.
Saying that they're equivalent is blatantly false. You can replace the word cannabis with alcohol and you'd just have to change schizophrenia to depression, personality disorders or just generally aggression.
I mean technically speaking, if we're talking about actual psychosis induced violence, then they're not actually terrorists, as they're just mentally ill. That being said, we seem to reserve that term for caucasians for some reason.
Edit: I wasn't disputing a correlation, I was simply saying that the Daily Mail jumping to conclusions about causation is not at all scientific or indeed based in any sort of fact.