Warhammer 40K Tabletop VII: Common Sense is not RAW.

[Cheesegear]

Lets extrapolate this even more (using real pieces as an example) The SM command sprue includes a set of kneeling legs (so no conversion) and you like the idea of your marines taking aim while kneeling (perhaps its a defense oriented army whatever your reasoning for liking the look) So you make a whole army with those legs.

Exactly. And that's why units where the players devise entire units with the 'kneeling' legs have been disallowed. You're spot on. You'll get no argument from me.

Unless you were being satirical to prove a point. In which case you are accidentally 100% correct.