It could also be a term used in some very specific cultural or literary references in a symbolic way that has nothing to do with the inappropriate meaning. For instance, in a fable where a mother figure is wrongly associated with a situation that seems to parallel the idea but is really about loyalty and misjudgment in a non - sexual way.
In a non - inappropriate sense, perhaps it could be a very misnamed or misconstrued situation. For example, if there is a misunderstanding where a mother is wrongly accused of something that gives a false impression similar to the negative connotation of 'cuckold', but in a completely innocent and family - related matter.
Another way to think about it is in a metaphorical sense within a community or family dynamic. Maybe there is a situation where a mother is put in a position where she seems to be 'betrayed' in a non - sexual way, like in terms of trust within the family, but the term is being used very loosely and creatively, not in the traditional and inappropriate sense.