So. To say that you can't write a ii6/4 is insisting that a cart pull the horse it seems to me.
Part-writing came before chords. Chords were not always the thing. So look at this example, it's exemplary part-writing. The principles of eg., contrary motion don't exist in order to agree with chord ideation or get you out of a problem, it exists qua part-writing. It's 'clean', I don't quite know how to articulate this, it's done because it's beautiful.