But how does this work? Is it just a way of destroying Bitcoins without actually destroying them (ie destroying Bitcoin and creating Sidecoins and vice versa creating Bitcoins and destroying Sidecoins, "converting" them 1:1) at the protocol level? I suppose cypherdoc's argument is that assuming Sidecoins will be valued less than Bitcoins of equal convertible value, people will be arbitraging that.

If I have understood correctly, then this doesn't seem a problem. To profit off this arbitrage, you need to buy Sidecoins (for USD say) and sell them for Bitcoins (selling those again). Thus the price has to rise to a level where friction prohibits arbitrage. It sounds like we're discussing a perpetuum mobile here. Either that, or I still misunderstand.