@ZellusYou are confused.
The Author Exclusion category excludes all stories written by the authors you list on the Author Exclusion page from certain lists displayed by SOL. This exclusion category has nothing to do with the codes listed in an excluded author's stories.
The Category Exclusion category excludes all stories from certain lists displayed by SOL that contain the codes you select on the Category Exclusion page for exclusion. So when the Preferences for Categories Exclusion Site-wide page displays 'Stories Excluded by your Selection: 4221', the stories being excluded are excluded because of codes selected on the page. The stories excluded have nothing to do with the author that wrote the stories.
Now to explain what I meant by 'certain lists', SOL displays two types of lists. There are the lists that SOL creates without being requested to do so by a member, such as the New Stories list. There are also lists that SOL creates when requested to do by a member, such as the lists created using the Category Search function.
In generating a list such as New Stories, SOL checks the member's author and category exclusions and excludes stories written by an excluded author and stories that contain an excluded code. Evidently, the exclusion does not affect stories added to the list before the exclusion was defined.
In lists generated by functions like the Category Search function, SOL includes all stories that meet the requested search criteria, to include stories written by an excluded author and stories containing an excluded code. For example: if you excluded the Ma/Ma code and your search criteria included the Ma/Ma code, then the resulting list will contain stories that include the Ma/Ma code.