Hide assignee display for certain users

I would like to hide the assignees that are working on the tickets from a certain group of customers.
In administration/workflow I managed to set the field assignee to "read only". With this setting the user cannot see or choose the assignee in ticket detail view anymore. So this already solved part of the problem.

When viewing the list of tickets the user can still see the assignee though. (see screenshot). Is there any way of getting rid of this column?