With most of your points I would say - not skipping is not a neutral choice, it's easier to ignore potential consequences, but (for example) what if he achieves less because he switches off? What if he resents you not skipping him?
With #5 I totally relate. I am holding out hope to be able to send my HG DD to a private school by yr5. Right now I feel like she needs a second skip to be instruction at her level at our local public, but I am pretty certain she would not need that skip at the private school, so much so that if she does go private for 5th we may need to reverse a second skip... That's tricky. And it's absolutely not an option for us to just send her now.
I know, I know. You are right. He has already switched off at school. "Mom I go to school to see my friends. I don't go there for learning. Learning happens at home." And last year, he was really frustrated and angry by about the 3rd month of school. I don't want that to happen again.
Maybe I should consider just putting him in third now. I'm sure that it will involve a long drawn out process. He does, though, have one friend that he doesn't want to leave behind. That's it. In fact, it was just that friend that he gives as a reason to stay in 2nd grade this year.
