OK, Gumby, it seems you are a little Pokey in the head. "Don't quote tax law"? Go to the damn IRS site and read it, then. A normal stock split is not declared as a dividend, you just get two shares for one (if it's a 2:1 split). That kind of stock split is not taxable. THIS ONE IS A DIVIDEND. I don't know why they are doing this, but that is what they have stated. And if it's a dividend, it is taxable, unless it's in and IRA or other non-taxable account. If you don't believe me, call the company. Or you could just wait for your 1099 from your broker, and then not pay tax on the dividend, and get fined.
As I understand it, you will have 50 shares of Class A with basis $80, and 50 shares of Class C at basis "whatever UA.C opens at on April 8", which I assume will be the same as the price of Class A shares at first. Where they go from there is a question, but the lack of voting rights wouldn't seem likely to drop the price much. Note that this is a taxable transaction, since it is a dividend, and you will owe taxes on the value of the spun-off shares. Does anyone know of a similar situation in another stock and what happened?