I would have thought that storing capped beers on the side is good, simply due to the fact that a bad seal would not allow oxygen into the bottle as CO2 escapes. And why would it matter if yeast is on the side of the bottle or on the bottom as long as I move it to an upright position and allowing to settle before opening?
Why would it being on its side prevent oxygen from entering? The yeast thing doesn't matter, though. You can either do what you said (store it upright for a few days to let it settle back down) or just keep the bottle on its side until it's poured. The letter is extremely common in Belgium (but this is only with corked bottles).
O2 will get into a sealed bottle if given enough time. The partial pressure of the O2 is the driver. That is why SN went to the pry off cap - to slow the process down.
It's still pressurized and CO2 will want to come out regardless. The liquid does not prevent the gas dissolved within it from escaping.
Looks like I could make a decent living regurgitating everything I've learned on this and other websites onto paper and selling it to a magazine.
I think that the laying of corked bottles on the side is to keep the cork wet, cork swells when wet giving the bottle a tighter seal.
