Stock buy backs functionally work no different them dividends at the end of the day. Your returns instead of getting issued as cash from a dividend are in the form of higher share value. Taxed as short term or long term capital gains vs dividend.

Its a form of stock manipulation if you mean that buying stock increases the value of the stock. It doesn't mean its a form of manipulation in some kind of illegal unethical way that i think this comment thread is trying to make it sound.