The logical impossibility depended on how you couldn't have conversations about consciousness without it. If you're the only thing that exists how can I disagree with you about it? How did you learn about it from a philosopher?
Had I read the argument from someone else at an earlier date, I'd probably use an argument-from-difference like you are. Such a scenario is more than logically possible- I might have actually considered the problem in the past. I have no doubt that the person who had once disagreed with OI is me.
Do you want to take this to PM, if only to save on your karma?
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.