If there was a requirement for passengers to walk forward, into the front unit for a short platform I'd understand the company-imposed rules (not ORR or RSSB), however the fact that all platforms fit six cars and even if some were short, ASDO allows customers off at the precise number of doors... ergo the company argument doors must be open on safety grounds, fire safety etc is baseless. Their sole remaining argument is for customer experience - however when it comes to the ASB-filled line those double units are mostly on, it's probably better the staff close the connection doors over and work away from the passengers to ensure the resilience of the service. Northerns CAF mess should not be allowed to spread - trains heavily delayed or given not to call orders as the staff can't get to or safely remain at the mid saloon panel during overcrowding, ASB, events, trouble etc.
Long term it would be an aspiration to have the connection doors open, I get it - however modifications need to take place - perhaps remove the huge seat on the second mans side & added a flip down, modify one side of the connector doors - all costs money but the person who ordered them to the current specification failed to consider the what if... ie assumed DOO would happen.