Apple TV was not about profit, Another possibility they might do a software update which would increase the performance (by activating the second core) when some new capabilities(server/cloud side) are available
http://blog.macsales.com/9102-secret-firmware-lets-late-08-m...
Either way, that isn't what is happening here. This is just CPU manufacturing 101. New chip, new processes, high bin rate. You mitigate this as much as possible by disabling features on binned chips to make them sellable. Intel has done it a number of times, typically when making a big change like the introduction of the Core Duo.