One justification for this is that the imputed "income" you get from being an owner-occupier (ie the rent you would have otherwise paid but saved) is not taxabl

One justification for this is that the imputed "income" you get from being an owner-occupier (ie the rent you would have otherwise paid but saved) is not taxable. Although I don't know about Germany specifically, I suspect this is exactly the position you'd be in if you followed through with this plan - the company would have to pay tax on the rent. And you wouldn't be able to get around this by reducing the rent say to zero because it's a related party so the company would likely be taxed on an imputed market rent.