Firstly, totsuka seals a persons soul after they have been peirced, irrelevant,
please provide proof that Totsuka has a 'limit' to the amount/speed of/on a person it can seal.
I can not prove a negative with a manga scan. That's why I asked you for a manga scan where it says Totsuka sword seals Souls specifically. And told you, you wouldn't find one because that's not what the blade does. The Blade seals everything it touches. Not only souls, everything. And puts everything it seals under genjutso. Now it clearly did not seal everything it touched as the snake got out, not to mention that Sasuke was inside that mess too and didn't got sealed either. That's why, like everything else in Narutoverse, the blade is over hyped by the characters.
Now to the speed, what is speed? You can define the speed of an event, example a sword sucking in a giant 7 headed snake and divide the mass of said snake by the time it took to be sealed, it wasn't instantaneous, so that gives you something like pounds per second. Just an example. That would define the speed of the sealing.
yes Oro 'ejected' to give a hint that Oro might come back, which was revealed in the next chapter to be burned i beleive. (correct me if im wrong please

) to dash that hope.
So you said it yourself he ejected so that he could escape being sealed, and he succeeded. Only to get accidentally killed by amaterasu. For Oro that was end of the line. He failed to survive that day it was his end. Just like the end came to Madara years before, and to Zabuza on Naruto's Bridge and for all of the other dead that were brought back to the living world by Edo Tensei, which I'm sure would not be qualified as a success by Orochimaru. He didn't wanted to die he wanted to escape with his life. But he got killed.
So he evade being sealed but he got killed. That's what Kishi showed us.
against your arguement.
A - hes not coming back because you cant escape being sealed
B - people who didnt see that snake are morons, people who acknowledge it but debate if it contained the entirety of Oro's being are knowledgeable and worth listening to (both of us for even having this debate

)
C - Kabuto used "oro's" DNA to recreate his body within his own (using the ability of the twins to morph his cells together).
All of these people's souls are either 'dead' - the sound 5. Or are sealed (and have merely become soulless bodies within Kabuto) - thats why when Oro's head flung out - his body - his soul never took control. His soul had been sealed and could not be brought back by edo - whilst his body could be scientifically regenerated (most likely) through use of Erasumas Darwin's theory of spontaneous regeneration.
Now every body in Naruto verse thinks that Itachi sealed Orochimaru, we the readers are the ones who know he didn't.
And the only person who could find out if Oro is dead rather than sealed is not interested in reviving Oro as he assimilated Oro into himself already.