If you are really that upset about it, why not look into getting 2 rooms at another value? Last September I went to WDW with my kids & my parents so there were 5 of us. We wanted to get a family suite at ASMu but it turned out to be significantly CHEAPER to get 2 regular value rooms than one family suite. I'm not sure what the current rates are for when you will be there, but it's at least worth looking it up and who knows, it might make you eligible for a discount. The family suites so far have never been eligible for discounts, because there are so few of them. But as everyone else here has pointed out, the All Stars are almost on top of each other and it really would be a very quick walk to another resort's pool.
I will also be at ASMu while the pool is closed - we plan to either visit the other pool or one of the pools at the other All Stars. We are also planning a day at a water park so we might not even need the pool.
Are you absolutely certain the kiddie pool is closed too? If it is anything like the ASMo resort, the kiddie pool is separate from the main pool, although it is in the same area. I have not received the letter that you got, but I have read online about the MAIN pool being closed but I don't recall it saying anything either way about the KIDDIE pool being closed too.
As for the CM you talked to, many of the CMs you get on the phone are not actually located AT WDW, so they won't know every detail (such as walking distances) firsthand. In my opinion, the most reliable source of information is to look online at trustworthy websites for up to date information.