It was not even slightly capable of performing that mission. It would have been swatted like a fly and all those ships sunk and most of those men killed. It was in fact a suicide mission had the Powhatan showed up as all the ships had believed it would.
I've read what the Confederates had set up. Anderson had passed this information to his leadership, and so they too knew what sort of cannon fire they would be facing. Only a small portion of the cannon force fired on Sumter. The bulk of it was held in reserve to deal with the force Lincoln sent down.
It is clear to me that it was no accident that the Powhatan did not rendezvous with the other ships and force their way in. Anyone who knew what was arrayed against them would have realized they would have been destroyed.
Lincoln only needed the Confederates to think he was sending in an attack, and that's why he let the ships orders go through normal channels, while his secret order to Lieutenant (two ranks below captain in the Union Navy at that time.) David Porter sent the command ship elsewhere without anyone knowing it wasn't going to Charleston.
Mister history buff. Find out how many cannon batteries were held in reserve to deal with the attacking fleet. Then tell me if you think those ships could have survived that.
According to this source, the total was fewer than 50 Confederate cannon, though seems to me I've seen other sources saying hundreds.
Anderson had 60 cannon, though only 21 available for use.
By the way, I notice from this source that Fox did send resupply boats to Fort Sumter, but they were turned back by Confederate fire.
So the intention was to send them again, in the dark on April 12.
That didn't work, only because of high seas, and by the next night Anderson had surrendered.
So the point here is: only bad weather prevented Fox from completing his mission to resupply Fort Sumter before Anderson surrendered on April 13, 1861.
Lincoln's resupply mission was far from impossible or unrealistic, simply suffered from bad weather & poor timing.
No good reason to read more into it.