I'm with the Stonehenge Alliance on this one. The final statement in your post by McMahon and Snashall ...
“We can’t just let the highway engineers reach for off-the-shelf solutions – but if we get this right there is a chance of doing something which finally rejoins the two halves of this amazing landscape, and which can also set the standard for other ancient sites across the world.”
is commendable but how any professional archaeologist can talk of Stonehenge setting the standard for other ancient sites across the world leaves me speechless. Its a nightmare ... and so sad. The idea a lone traveller could happen upon it with surprise and delight long, long gone.