I think this is the key quote:

"Miles awarded as a promotion for opening an account, such as a bank account. Such miles are taxable, according to the IRS. Responding to queries about the Citibank accounts, an IRS spokesman said, "When frequent-flier miles are provided as a premium for opening a financial account, it can be a taxable situation subject to reporting under current law." This makes the miles akin to toasters or iPods given out as promotional gifts."

However - the question still arises what value do you put on the miles. 30,000 should be more like $300 rather than the $750 indicated in the article.