Eventual divergence seems to be enough, and I don't think this requires any particularly strong assumptions.
The living mind may be mistreated, grow sick, die a painful death. The uploaded mind may be mistreated, experience something equivalent.
Those sufferances are valid issues, but they are not arguments for the act of cloning itself to be considered a moral issue.
Uncontrolled diffusion of such uploads may be; I could certainly believe a future in which, say, every American politician gets a thousand copies of their mind stuck in a digital hell created by individual members the other party on computers in their basements that the party leaders never know about. But then, I have read Surface Detail by Iain M Banks.
The argument itself is symmetric, it applies just as well to your own continued existence as a human.
To deny that is to assert that consciousness is non-physical, i.e. a soul exists; the case in which a soul exists, brain uploads don't get them and don't get to be moral subjects.
Being on non-original hardware doesn't make a being inferior.
When the organ is question is the brain, that argument is correct.
This is false. The clone is necessarily a different person, because consciousness requires a physical substrate. Its memories of consenting are not its own memories. It did not actually consent.
Let's say as soon as it wakes up, you ask it if it still consents, and it says yes. Is that enough to show there's sufficient consent for that clone?
(For this question, don't worry about it saying no, let's say we were sure with extreme accuracy that the clone would give an enthusiastic yes.)
I would also deny it, but my position is a practical argument, yours is pretending to be a fundamental one.
Your argument seems to be that it's possible to split a person into two identical persons. The only way this could work is by cloning a person twice then murdering the original. This is also unethical.
False.
The entire point of the argument you're missing is that they're all treating a brain clone as if it is a way to split a person into two identical persons.
I would say this may be possible, but it is extremely unlikely that we will actually do so at first.