Technically yes you could do this through the use of customized workflow, however it would be very tricky as you would need to be able to access the folder symbolic naming structure to be able to use it for identifying the folder that is being ''selected'' for viewing. Within the newer ''smart repository'' the naming structure is a series of A and B strings to identify the parent structure for the hierarchy. For example within a certain project a folder would be say ''AAA'' where A if the main parent and AA is the parent of your subjective folder. You'd need to find that folders naming construct so that you could compare against it and thus make the folder readonly when certain groups select that folder. SO you'd need to access that naming structure and then be comparing it against the list to be limited while also comparing the user against a known list of ''allowed'' users and setting the folder status as directed (read only or full permissions as needed).
As you can see it would be involved and require that you were able to access the static naming structure for the folders to be limited.
Hope this helps somewhat,