Thanks for the comments and support everyone.
Yes, we certainly realize that the high school credit issue is potentially serious. But it is also a potential false alarm, so we can't let fear of it make us make decisions we could later regret. It could be that the rules later change in our favor, or maybe the rules are already in our favor and we just need to research it ourselves instead of relying on a school administrator's word for it, or maybe the powers that be just haven't put much thought into these scenarios and would be willing to accommodate and maybe change rules. After all it's pretty silly that one wouldn't get high school credit (or better), for passing high school courses before high school, or passing college courses while in high school.
And what if he didn't get credit. Well we'd just be in the same boat as homeschoolers, and homeschooling is always an option anyway. We could make a homemade transcript just like homeschoolers have to, and back it up with proctored results.
Now "repeating classes that were too easy the FIRST time around" would certainly not be a happy outcome, but maybe a possibility would be to just sit the "end of course exam" to get credit for each earlier-completed course while in high school.
We have a clear idea of what we want. We want single subject accelerations whenever appropriate. (In a virtual school we don't skip, we just go faster.) But we don't want whole grade-level acceleration since that just handicaps you in grade-based competitions and tests, and we don't want a fast-track to college.