No, I've made a substantive observation about the point actually at issue: you implied that every country necessarily has immigration controls at its border, which in fact is not true.
You had tried to support that claim by making an analogy with biological cells, and it pleased me that in fact my counter-point fits into that analogy, but it doesn't really matter: if it turns out that the cell-analogue of "every country has to have immigration controls at its border" is true, all that means is that cells were a bad analogy because, again, it is simply not true that every country needs immigration controls at its border.
I am not a cell biologist so this might be wrong, but my understanding is that cell membranes are in fact permeable to water and don't have any particular ability to regulate the movement of water in and out of the cell. The rate at which that happens will be affected by e.g. concentration of solutes on each side, but it's not a thing a typical cell has mechanisms for controlling. I think there are such mechanisms in some cells in the kidney, but AIUI while most (all?) cells have aquaporins there's nothing adjusting their permeability. But, once again, while this is all interesting in its own right it tells us nothing about what countries can, or do, or should regulate. If some researcher makes a stunning discovery that overturns our understanding of what cell membranes do, the appropriate adjustment in national-border regulation will be zero.
