It's a repair in the sense that it's definitely not a repair and is compelling evidence of something that isn't a repair.
I forgot to mention that the phrase was actually "re-excavate and reprofile". Now I know what re-profile means, it means drill away the existing tunnel walls and make a bigger tunnel.
So the literal, unspun meaning of one of the few repair options put to them was "to drill a new tunnel right to the centre of Silbury for reasons unknown."
I've written suggesting this might cause a bit of a fuss, but their reply made no reference to it.