Views entity reference field condition
Here is a zero coding solution. 

Create a new view: 


CONTEXTUAL FILTER add Node id (since workers is a content type), so we have the id of the worker. 
RELATIONSHIP add Referecing Entity, checkmark require relationship.
Fields: Add Title 


At top you will see a select box, select the relationship option.
Unchecked Link this field to the original piece of content
Click on NO RESULT BEHAVIOUR, put Green
Click on REWRITE RESULTS, checkmark Rewrite the output of this field, put Red

In FILTER CITERIA add type and select Workers. 
In FILTER CRITERIA add the List Field (the one that contains Red or Green) and put is equal to Red and select relationship option at top.


for PAGER put 1 item. 





Install and enable Views Field View

Now in your List of All Workers view:

In FIELDS add Node ID and checkmark hide field from view.

In FIELDS now Add the View Fields view field.


Select the previous view we created. 
For argument, Click on replacement patterns, and use the Node ID token to pass as an argument.