Maeshowe 16
Image by A R Cane

Seems a bit OTT to me.
Yes, you do have to cross a minor road to the site but it is hardly the M4!
Are they saying adults are incapable of spotting the infrequent car which uses the road?
What do they want, a zebra crossing?
I could go into a 'Health and Safety gone mad' rant but you know what I mean.....

I can see a potential hazard when there are large groups perhaps.

I'm astounded nobody has been knocked over at Avebury tbh.
Either crossing at the Sanctuary, or from Silbury over to WKLB. Or even in the henge itself.