This is one post on one forum by one person. Maybe he invented botany(judging from his posts over there I doubt it), i dunno, but Ionmagic there is the only person I can find referring to cannabis as an annual, deciduous plant. In fact, he's the only person I can find calling ANY plant annual and deciduous. Aren't you one who advised not to just trust random forum hearsay? These are the theories of somebody who finished their first grow in November and you're going to quote that to somebody else as truth?
Denying an annual plant the winter that ends it's life cycle does not make it deciduous. And that is exactly the logic offered in your link that supports calling it deciduous and annual at the same time.