Activity Story Steam - Exclude Specific Groups

We have a couple of groups that are public and need to be public, but I would like to be able to exclude them from inclusion in the Activity Story Stream except if the widget is used in those specific groups. It seems that I should be able to add an exclusion filter to the query, but I don't see a method for doing that. As an alternative it would seem like maybe when parse-query.vm is looping through the subgroups that the specific subgroups could be skipped. Does anyone have an approach/solution for this problem?