I think I saw something about that, either in the material that you and others have presented, or in some of my own reading on the topic.
Again, why secrecy for a "re-supply" mission?
A shrewd man would know that there was no way he could hide his shipyard doings from Southern spies or sympathizers, but he could leave them guessing as to what were his intentions, knowing they would assume the worst.
That the name "Baltic" would be painted out before the ship sailed, would be noted. The reason why it was painted out could only be conjectured, but it would most definitely leave the impression that someone was up to no good.
DISPATCHES FROM THE EDUCATION APOCALYPSE: “I started giving quizzes to my juniors and seniors. I gave them a ten-question American history test… just to see where they are. The vast majority of my students – I’m talking nine out of ten, in every single class, for seven consecutive years – they have no idea that slavery existed anywhere in the world before the United States. Moses, Pharaoh, they know none of it. They’re 100% convinced that slavery is a uniquely American invention… How do you give an adequate view of history and culture to kids when that’s what they think of their own country – that America invented slavery? That’s all they know.”
https://pjmedia.com/instapundit/239847/#respond
What did anyone expect when such propaganda is constantly spouted by Union Apologists?
Then there was the case of the Powhattan flying "English colors" when she first approached Pensacola (site of Fort Pickens) [Link].
Whether the ship's name was painted out or not (I've not seen where it was) would be reasonable, considering that President Buchanan's January resupply ship, Star of the West was fired on by secessionist batteries and forced to withdraw.
So clearly, they knew both it's origin and purpose.
If painting out Baltic's name could cause enough confusion in Confederate minds to let it pass does seem to us dubious, especially since Lincoln told Gov. Pickens a resupply ship was coming.
But perhaps at the moment of painting, somebody hoped it might help.
On the 4th of February, 1861, the Confederate Congress, composed of delegates from the six southern states met at Montgomery, Alabama and completed the secession movement by composing and adopting their own constitution. This ended the slavery problem for the Union states.
The issue of slavery no longer had any political influence or social impact on the Union states or the territories. Those that remained preoccupied with it were needing a rationalization for their personal issues.