The "consensus" here is not to "ban the public" but to better explain the damage problem to them and appeal to their better nature. If they are going to say "well some achaeos and the occasional film crew and official Druid goes up therefore I'm going to as well" I'd suspect they are looking for cover to do what they intended to anyway.
Personally, I would be against renovating and throwing open the main path as that would result in 500x more people going up and a commensurate increase in erosion.
Perhaps we should have a new topic to discuss 'what does Silbury mean to you' ... why for example does the official Druid need to go up there when Silbury can be appreciated (venerated even) from so many other high vantage points nearby. For myself, it is far more than an ancient mound of grass covered chalk - hard to put into words.