I'm sorry that you got the run around. We had a few meetings like this. For us, persistence did eventually pay off.
I think that any time you are presenting something that's never been done before, you've got an uphill battle. But we have found that once the teachers finally believe you (oh, yeah, I guess this kid is different), then things start to change. The trial run might be a good opportunity.
We also face issues with writing, which prevented the old school from advancing our DS in math (we moved to an HG school midyear, which doesn't see that as an impediment but simply something to work on).
You never know, the school might surprise you in a good way. Maybe when they become familiar with the IAS and how it really makes the decision making process easier, they will embrace it.
Good luck!
