Hmm... I'm now thinking... Could one make a plastic bit that is held by the same parts the headphone would be, but make it to tolerance so that it doesn't push the bent sensor closed? And then make the appropriate contact to supply an "antenna", which could then be a little nub-type antenna sticking out the top? That would probably be pretty cheep to make, and would find a nice audience for most Nokia devices that use their headset as an antenna, N900 included.