It's a journalistic piece, actually. Normally, in such writing you get the colloquial use of 'theory', as NS indicated. For example, 'I have a theory that blondes have the fun, brunettes have the cash'. But people use 'theory' like this, even when talking about science, to mean 'idea'.
It's no good wishing that the colloquial sense would go away, as it's not going to.