The WorldCat.org citation function will try to fit any author in 1xx or 7xx fields into the citation (within reason or style limitations). If the author has a relator code like "editor," we will try to get more specific on how it’s cited (again, fitting into the citation style guidelines).
If there is a different relator term, such as "introduction author," it may fall into the default 'is an author’ of the record and is cited as such.