In this context it doesn't have anything to do with a spouse. Cuck is an all-encompassing term that is mostly used as a way of referring to submissive beta males. In this case it refers to a programmer who allows themselves to be exploited and enables users to become useds by permitting other developers to build proprietary spyware on top of their own software. You need to divorce the etymology from the current usage(s) of the word, this is common across the English language.