Seeing Red (Signs)

The use of these signs is causing me some concern. What is the cyclists position if they chose not to walk and are involved in an incident? What is the position if they obey the signs and are involved in an incident?
The ongoing road works on the A4130 between Milton Road and the Hawksworth estate have plenty of anti-cycling signs. Including several signs placed in the gutter advising ‘cycle lane closed’ – there is no cycle lane. This is not a route I cycle but I saw a cyclist who diligently followed the instructions to dismount, he then waited for a green light and pushed his bike the length of the road works in the middle of the lane with a number of cars patiently following.

Is it worth contacting the Oxfordshire County Council (I believe they are responsible for this)?
https://www.oxfordshire.gov.uk/cms/public-site/roads-and-transport

If they are not official road signs, then in my opinion they shouldn’t be there.
It seems a bit like me putting my own “no parking” sign up to stop people parking outside my house.

Also, when I last drove through them they were quite long so they probably just don’t want cyclists riding through there.
Mind you, last time there were road works with lights there I could easily keep up or was even slowed down by cars going through them.

Oftentimes they have a thingy on the traffic lights to detect oncoming vehicles and decide if the vehicles are still between the traffic lights to do the traffic light control – these often don’t work for bikes. Maybe this is the issue?

See this article regarding similar situation in London: reminding the contractor of cyclists’ legal right to use the road got them to change the signs:
http://road.cc/content/news/130401-cyclists-dismount-no-thanks-says-rider-who-persuaded-contractor-change-signs