the design decision could be to change the startup process in a way that provides no more hooks for a boot menu. for example. or use some of the nice and well-known "no open driver"-tricks that prevent you from running another OS...

if they do this, i guess it wouldn't be worth the effort to change these parts of maemo for the non-subsidized devices. - the number of people who care about being able to run alternate OSs is just too small, isn't it?

it's just a thought, though, something that could happen. (if this ad-based thing is true at all...) i'm not saying they'd need to do it and there'd be no other way.