Surely the moral responsibility of a manager ordering such work done is just as great as that of an Engineer carrying it out. So why is the debate entirely about the Engineers refusing to do the work, and nobody is talking about managers refusing to give the order?

I'm not saying that anyone should refuse, I think that's a foolish idea and as has been pointed out the Government has many tools and sanctions available it can use to compel compliance. I just find the current debate somewhat blinkered.