It seems as if you did not quite read the order.
I will give it to you again:
(Fox) “He is charged by authority here, with the command of an expedition (under cover of certain ships of war) whose object is, to reinforce Fort Sumter.”
Reinforce is action, not preparation.
So your claim is that, despite the fact that we can read Fox’s actual orders to only attempt to reinforce if the attempt to land supplies alone is opposed, his REAL orders were to land reinforcements either way. Is that about it?