I think the point is to us, all henges are important, when one is under threat, all henges are under threat. In terms of Thornborough, my aim is to allow the public to see that it is central to a feature that modern man has yet to understand, and should therefore be preserved. The aim of the developer is to fund a nice bit of research and say it is understood. It is not good enough to wipe it with a few modern scans and say "it's linked with the pattern of the stars", an explaination which (in my view, given the local circumstances) will allow the feature to be destroyed.
Hope you get what I'm saying, slightly the worse for wear - beers etc.