If something is granted it's not imposed. Those two things are mutually exclusive. If Engels was honest in his argument he'd have used "imposed authority" to characterise what anti-auths were criticising, not the general "authority".
When I submitted arguments like these to the most rabid anti-authoritarians, the only answer they were able to give me was the following: Yes, that’s true, but there it is not the case of authority which we confer on our delegates, but of a commission entrusted! These gentlemen think that when they have changed the names of things they have changed the things themselves. This is how these profound thinkers mock at the whole world.
If something is granted it's not imposed. Those two things are mutually exclusive. If Engels was honest in his argument he'd have used "imposed authority" to characterise what anti-auths were criticising, not the general "authority".
You're almost there.