No, the NO CYCLING sign is longstanding. It was there over 15 years ago:
https://maps.app.goo.gl/aYbpnChBXXLf8kyQ8

I suspect the other mapper had not visited the site and was trying to mislead cycle routing tools to follow Sustrans mapping, which often fails to correspond to legal or practical routes. 

The map needs to reflect the world as it is - not the wishful thinking of Sustrans.