I think he is trying to tell you that you will need to revert it back to veg in order for the roots start growing. When you did this, the plant would no longer be in the flower stage, and would start to grow again like it normally would, you could grow the plant bigger, just like you would any normal clone, and then start to flower again later when you have more than one bud site, lol.
I'f you reverted it back to veg just long enough for the roots to grow and take hold, then you could potentially put it back into flower and would be kinda like a bud growing out of the dirt... but what is so much better about that than just leaving it on the plant to finish up? What would be the point of this? you would probably only be reducing the yeild of that bud, as it would screw with it's cycle and it would need to Bud-Mass and THC producing energy on other things like rooting itself and getting used to rapid changes between flower and veg cycles. you could turn it hermie with all that stress. You would get more out of the bud by just leaving it on the plant anyway, trust me. This isn't really worth it even as an "experiment" not trying to be a dick or anything, just trying to help you out. If you really want a bud that grows out of the ground, try a lowryder, lol.