The premise of the position is that it's theoretically possible to create a person with memories of being another person. I obviously don't deny that or there would be no argument to have.
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.
> 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.