The rules modules has default actions setup to unpublish nodes but not comments. Do I need to use PHP to unpublish a comment?
If you choose the action "Set a data value" and a comment is visible to the action (e.g. because the triggering event is "After saving a new comment") then the data selector will let you choose
which you can then choose to set to "Published" or "Unpublished", or (via a data selection) to another available value.