1. This site seems to be unique in its differentiation between "flush" (flooding the container to remove a harmful condition such as salts or too-high nutrients) and "cleanse" (watering without nutes so the plant consumes its stored nutes and, if the water is ph'd, remaining nutes in the soil).
It sounds like you're calling the "cleanse" a "flush"(?) and referring to another site where they may practice flush followed by 10 days of water only. If that's the case, it may be unclear how much those external parties may be realizing the flush is harmful, but not the water-only cleanse.
Either way, the differences in terminology may lead to confusion. (I.e., I think most here agree "flushing" is an extreme action to be avoided.).
2. Referring to the bolded quote, "use" should mean "metabolize?" It seems like there would be a difference between plant material that is a product of metabolized nutrients and material that contains stored nutrients.
Although, I don't understand that difference, how it works, etc.